diff --git a/neo3-gui/neo3-gui/Helpers.cs b/neo3-gui/neo3-gui/Helpers.cs
index 020766bd..c6a7e7eb 100644
--- a/neo3-gui/neo3-gui/Helpers.cs
+++ b/neo3-gui/neo3-gui/Helpers.cs
@@ -112,6 +112,32 @@ public static string SafeSerialize(this ContractParametersContext signContext)
             return signContext.ToJson().SerializeJson();
         }
 
+        /// <summary>
+        /// create tx by script and signer
+        /// </summary>
+        /// <param name="wallet"></param>
+        /// <param name="script"></param>
+        /// <param name="signers"></param>
+        /// <returns></returns>
+        public static Transaction InitTransaction(this Wallet wallet, byte[] script, params UInt160[] signers)
+        {
+            var cosigners = signers.Select(account => new Cosigner { Account = account }).ToArray();
+            return InitTransaction(wallet, script, cosigners);
+        }
+
+        /// <summary>
+        /// create tx by script and signer
+        /// </summary>
+        /// <param name="wallet"></param>
+        /// <param name="script"></param>
+        /// <param name="signers"></param>
+        /// <returns></returns>
+        public static Transaction InitTransaction(this Wallet wallet, byte[] script, params Cosigner[] signers)
+        {
+            var tx = wallet.MakeTransaction(script, null, null, signers);
+            return tx;
+        }
+
 
         /// <summary>
         /// append sign to signContext
@@ -695,7 +721,7 @@ public static byte[] TryGetPrivateKey(this string privateKey)
             }
             try
             {
-                return Wallet.GetPrivateKeyFromWIF(privateKey); 
+                return Wallet.GetPrivateKeyFromWIF(privateKey);
             }
             catch (FormatException)
             {
diff --git a/neo3-gui/neo3-gui/Models/Contracts/ValidatorModel.cs b/neo3-gui/neo3-gui/Models/Contracts/ValidatorModel.cs
new file mode 100644
index 00000000..e5b5dd61
--- /dev/null
+++ b/neo3-gui/neo3-gui/Models/Contracts/ValidatorModel.cs
@@ -0,0 +1,20 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Neo.Models.Contracts
+{
+    public class ValidatorModel
+    {
+        public string Publickey { get; set; }
+
+        public string Votes { get; set; }
+
+        /// <summary>
+        /// In Use
+        /// </summary>
+        public bool Active { get; set; }
+    }
+}
diff --git a/neo3-gui/neo3-gui/Models/Contracts/VoteResultModel.cs b/neo3-gui/neo3-gui/Models/Contracts/VoteResultModel.cs
new file mode 100644
index 00000000..133830c2
--- /dev/null
+++ b/neo3-gui/neo3-gui/Models/Contracts/VoteResultModel.cs
@@ -0,0 +1,13 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Neo.Models.Contracts
+{
+    public class VoteResultModel
+    {
+        public UInt256 TxId { get; set; }
+    }
+}
diff --git a/neo3-gui/neo3-gui/Models/ErrorCode.cs b/neo3-gui/neo3-gui/Models/ErrorCode.cs
index c84289a8..7b2d05e0 100644
--- a/neo3-gui/neo3-gui/Models/ErrorCode.cs
+++ b/neo3-gui/neo3-gui/Models/ErrorCode.cs
@@ -62,7 +62,9 @@ public enum ErrorCode
         ExecuteContractFail = 20027,
         [Description("Unknown contract. ")]
         UnknownContract = 20028,
-        [Description("Contract already onchain. ")]
+        [Description("Contract already onchain.")]
         ContractAlreadyExist = 20029,
+        [Description("Validator already exits.")]
+        ValidatorAlreadyExist = 20030,
     }
 }
\ No newline at end of file
diff --git a/neo3-gui/neo3-gui/Services/ApiServices/ContractApiService.cs b/neo3-gui/neo3-gui/Services/ApiServices/ContractApiService.cs
index c2337c0d..4b443c7b 100644
--- a/neo3-gui/neo3-gui/Services/ApiServices/ContractApiService.cs
+++ b/neo3-gui/neo3-gui/Services/ApiServices/ContractApiService.cs
@@ -2,9 +2,11 @@
 using System.Collections.Generic;
 using System.IO;
 using System.Linq;
+using System.Numerics;
 using System.Text;
 using System.Threading.Tasks;
 using Microsoft.Win32.SafeHandles;
+using Neo.Cryptography.ECC;
 using Neo.IO;
 using Neo.IO.Json;
 using Neo.Ledger;
@@ -16,6 +18,7 @@
 using Neo.SmartContract.Native;
 using Neo.VM;
 using Neo.Wallets;
+using Neo.Wallets.SQLite;
 
 namespace Neo.Services.ApiServices
 {
@@ -35,7 +38,16 @@ public async Task<object> GetContract(UInt160 contractHash)
             return new ContractModel(contract);
         }
 
-
+        public async Task<object> GetManifestFile(UInt160 contractHash)
+        {
+            using var snapshot = Blockchain.Singleton.GetSnapshot();
+            var contract = snapshot.Contracts.TryGet(contractHash);
+            if (contract == null)
+            {
+                return Error(ErrorCode.UnknownContract);
+            }
+            return contract.Manifest.ToJson();
+        }
 
 
         public async Task<object> DeployContract(string nefPath, string manifestPath = null, bool sendTx = false)
@@ -57,7 +69,7 @@ public async Task<object> DeployContract(string nefPath, string manifestPath = n
 
 
             using var snapshot = Blockchain.Singleton.GetSnapshot();
-            var oldContract= snapshot.Contracts.TryGet(nefFile.ScriptHash);
+            var oldContract = snapshot.Contracts.TryGet(nefFile.ScriptHash);
             if (oldContract != null)
             {
                 return Error(ErrorCode.ContractAlreadyExist);
@@ -137,21 +149,13 @@ public async Task<object> InvokeContract(InvokeContractParameterModel para)
                 signers.AddRange(para.Cosigners.Select(s => new Cosigner() { Account = s.Account, Scopes = s.Scopes }));
             }
 
-            Transaction tx = new Transaction
-            {
-                Sender = UInt160.Zero,
-                Attributes = new TransactionAttribute[0],
-                Witnesses = new Witness[0],
-                Cosigners = signers.ToArray(),
-            };
-            using (ScriptBuilder scriptBuilder = new ScriptBuilder())
-            {
-                scriptBuilder.EmitAppCall(para.ContractHash, para.Method, contractParameters);
-                tx.Script = scriptBuilder.ToArray();
-            }
+            Transaction tx = null;
+            using ScriptBuilder sb = new ScriptBuilder();
+            sb.EmitAppCall(para.ContractHash, para.Method, contractParameters);
+
             try
             {
-                tx = CurrentWallet.MakeTransaction(tx.Script, null, tx.Attributes, tx.Cosigners);
+                tx = CurrentWallet.InitTransaction(sb.ToArray(), signers.ToArray());
             }
             catch (InvalidOperationException)
             {
@@ -189,6 +193,179 @@ public async Task<object> InvokeContract(InvokeContractParameterModel para)
             return result;
         }
 
+
+        #region Vote
+
+
+        /// <summary>
+        /// Get all working or candidate validators
+        /// </summary>
+        /// <returns></returns>
+        public async Task<object> GetValidators()
+        {
+            using var snapshot = Blockchain.Singleton.GetSnapshot();
+            var validators = NativeContract.NEO.GetValidators(snapshot);
+            var registerValidators = NativeContract.NEO.GetRegisteredValidators(snapshot);
+            return registerValidators.OrderByDescending(v => v.Votes).Select(p => new ValidatorModel
+            {
+                Publickey = p.PublicKey.ToString(),
+                Votes = p.Votes.ToString(),
+                Active = validators.Contains(p.PublicKey)
+            }).ToArray();
+        }
+
+
+
+
+        /// <summary>
+        /// apply for new validator
+        /// </summary>
+        /// <param name="pubkey"></param>
+        /// <returns></returns>
+        public async Task<object> ApplyForValidator(string pubkey)
+        {
+            if (CurrentWallet == null)
+            {
+                return Error(ErrorCode.WalletNotOpen);
+            }
+            if (pubkey.IsNull())
+            {
+                return Error(ErrorCode.ParameterIsNull);
+            }
+            ECPoint publicKey = null;
+            try
+            {
+                publicKey = ECPoint.Parse(pubkey, ECCurve.Secp256r1);
+            }
+            catch (Exception e)
+            {
+                return Error(ErrorCode.InvalidPara);
+            }
+            using var snapshot = Blockchain.Singleton.GetSnapshot();
+            var validators = NativeContract.NEO.GetRegisteredValidators(snapshot);
+            if (validators.Any(v => v.PublicKey.ToString() == pubkey))
+            {
+                return Error(ErrorCode.ValidatorAlreadyExist);
+            }
+            VerificationContract contract = new VerificationContract
+            {
+                Script = SmartContract.Contract.CreateSignatureRedeemScript(publicKey),
+                ParameterList = new[] { ContractParameterType.Signature }
+            };
+
+            var account = contract.ScriptHash;
+            using ScriptBuilder sb = new ScriptBuilder();
+            sb.EmitAppCall(NativeContract.NEO.Hash, "registerValidator", publicKey);
+
+            Transaction tx = null;
+            try
+            {
+                tx = CurrentWallet.InitTransaction(sb.ToArray(), account);
+            }
+            catch (InvalidOperationException)
+            {
+                return Error(ErrorCode.EngineFault);
+            }
+            catch (Exception ex)
+            {
+                if (ex.Message.Contains("Insufficient GAS"))
+                {
+                    return Error(ErrorCode.GasNotEnough);
+                }
+                throw;
+            }
+
+            var (signSuccess, context) = CurrentWallet.TrySignTx(tx);
+            if (!signSuccess)
+            {
+                return Error(ErrorCode.SignFail, context.SafeSerialize());
+            }
+            var result = new VoteResultModel();
+            await tx.Broadcast();
+            result.TxId = tx.Hash;
+            return result;
+        }
+
+
+
+
+        /// <summary>
+        /// vote for consensus node
+        /// </summary>
+        /// <returns></returns>
+        public async Task<object> VoteCN(UInt160 account, string[] pubkeys)
+        {
+            if (CurrentWallet == null)
+            {
+                return Error(ErrorCode.WalletNotOpen);
+            }
+            if (account == null || pubkeys.IsEmpty())
+            {
+                return Error(ErrorCode.ParameterIsNull);
+            }
+            ECPoint[] publicKeys = null;
+            try
+            {
+                publicKeys = pubkeys.Select(p => ECPoint.Parse(p, ECCurve.Secp256r1)).ToArray();
+            }
+            catch (Exception e)
+            {
+                return Error(ErrorCode.InvalidPara);
+            }
+            using ScriptBuilder sb = new ScriptBuilder();
+            sb.EmitAppCall(NativeContract.NEO.Hash, "vote", new ContractParameter
+            {
+                Type = ContractParameterType.Hash160,
+                Value = account
+            }, new ContractParameter
+            {
+                Type = ContractParameterType.Array,
+                Value = publicKeys.Select(p => new ContractParameter
+                {
+                    Type = ContractParameterType.PublicKey,
+                    Value = p
+                }).ToArray()
+            });
+
+            Transaction tx = null;
+            try
+            {
+                tx = CurrentWallet.InitTransaction(sb.ToArray(), account);
+            }
+            catch (InvalidOperationException)
+            {
+                return Error(ErrorCode.EngineFault);
+            }
+            catch (Exception ex)
+            {
+                if (ex.Message.Contains("Insufficient GAS"))
+                {
+                    return Error(ErrorCode.GasNotEnough);
+                }
+                throw;
+            }
+
+            var (signSuccess, context) = CurrentWallet.TrySignTx(tx);
+            if (!signSuccess)
+            {
+                return Error(ErrorCode.SignFail, context.SafeSerialize());
+            }
+            var result = new VoteResultModel();
+            await tx.Broadcast();
+            result.TxId = tx.Hash;
+            return result;
+        }
+
+
+        #endregion
+
+
+
+
+
+        #region Private
+
+
         /// <summary>
         /// try to read nef file
         /// </summary>
@@ -265,5 +442,8 @@ private async Task CheckBadOpcode(byte[] script)
                 context.InstructionPointer += ci.Size;
             }
         }
+
+
+        #endregion
     }
 }
diff --git a/neo3-gui/neo3-gui/Services/ApiServices/TransactionApiService.cs b/neo3-gui/neo3-gui/Services/ApiServices/TransactionApiService.cs
index 11aa3f8b..252f876b 100644
--- a/neo3-gui/neo3-gui/Services/ApiServices/TransactionApiService.cs
+++ b/neo3-gui/neo3-gui/Services/ApiServices/TransactionApiService.cs
@@ -46,7 +46,7 @@ public async Task<object> GetTransaction(UInt256 txId)
             model.Transfers = trans.Select(tx => tx.ToTransferModel()).ToList();
 
             var executeResult = db.GetExecuteLog(txId);
-            if (executeResult.Notifications.NotEmpty())
+            if (executeResult?.Notifications.NotEmpty() == true)
             {
                 model.Notifies.AddRange(
                     executeResult.Notifications.Select(n => new NotifyModel()
@@ -103,7 +103,7 @@ public async Task<object> QueryTransactions(int pageIndex = 1, int limit = 100,
         }
 
 
-    
+
 
         /// <summary>
         /// query all nep transactions(on chain)
diff --git a/neo3-gui/neo3-gui/Services/ApiServices/WalletApiService.cs b/neo3-gui/neo3-gui/Services/ApiServices/WalletApiService.cs
index 274f95a7..e5a13374 100644
--- a/neo3-gui/neo3-gui/Services/ApiServices/WalletApiService.cs
+++ b/neo3-gui/neo3-gui/Services/ApiServices/WalletApiService.cs
@@ -268,6 +268,25 @@ public async Task<object> ListPublicKey(int count = 100)
             });
         }
 
+
+        /// <summary>
+        /// list current wallet candidate address(only single sign address)
+        /// </summary>
+        /// <returns></returns>
+        public async Task<object> ListCandidatePublicKey(int count = 100)
+        {
+            if (CurrentWallet == null)
+            {
+                return Error(ErrorCode.WalletNotOpen);
+            }
+            var accounts = CurrentWallet.GetAccounts().Where(a => !a.WatchOnly && a.Contract.Script.IsSignatureContract()).Take(count).ToList();
+            return accounts.Select(a => new PublicKeyModel
+            {
+                Address = a.Address,
+                PublicKey = a.GetKey().PublicKey.EncodePoint(true),
+            });
+        }
+
         /// <summary>
         /// import watch only addresses
         /// </summary>