diff --git a/tests/test_apis/test_inferencers/test_diffusers_pipeline_inferencer.py b/tests/test_apis/test_inferencers/test_diffusers_pipeline_inferencer.py
index 98b49f6e7c..dbfeb5c6e8 100644
--- a/tests/test_apis/test_inferencers/test_diffusers_pipeline_inferencer.py
+++ b/tests/test_apis/test_inferencers/test_diffusers_pipeline_inferencer.py
@@ -2,6 +2,7 @@
 import platform
 
 import pytest
+import torch
 from mmengine.utils import digit_version
 from mmengine.utils.dl_utils import TORCH_VERSION
 
@@ -24,6 +25,17 @@ def test_diffusers_pipeline_inferencer():
             from_pretrained='runwayml/stable-diffusion-v1-5'))
 
     inferencer_instance = DiffusersPipelineInferencer(cfg, None)
+
+    def mock_encode_prompt(prompt, do_classifier_free_guidance,
+                           num_images_per_prompt, *args, **kwargs):
+        batch_size = len(prompt) if isinstance(prompt, list) else 1
+        batch_size *= num_images_per_prompt
+        if do_classifier_free_guidance:
+            batch_size *= 2
+        return torch.randn(batch_size, 5, 16)  # 2 for cfg
+
+    inferencer_instance.model._encode_prompt = mock_encode_prompt
+
     text_prompts = 'Japanese anime style, girl'
     negative_prompt = 'bad face, bad hands'
     result = inferencer_instance(