diff --git a/README.md b/README.md
index dd3ed5c8..7cf8125f 100644
--- a/README.md
+++ b/README.md
@@ -73,6 +73,10 @@ strategies.
 | Anthropic | ✅ | ✅ | ✅ |✅|
 | MidJourney | | ✅ |  |✅|
 
+To support different models in custom func(e.g. Model Comparison) , [follow our example](https://github.com/YiVal/YiVal/blob/litellm_complete/demo/configs/model_compare.yml)
+
+To support different models in evaluators and generators , [check our config](https://github.com/YiVal/YiVal/blob/litellm_complete/demo/configs/headline_generation.yml)
+
 ## Installation
 
 ```sh
diff --git a/demo/configs/headline_generation.yml b/demo/configs/headline_generation.yml
index 95f11fa7..48d92bf0 100644
--- a/demo/configs/headline_generation.yml
+++ b/demo/configs/headline_generation.yml
@@ -5,6 +5,7 @@ dataset:
     openai_prompt_data_generator:
       chunk_size: 100000
       diversify: true
+      # model_name specify the llm model , e.g. a16z-infra/llama-2-13b-chat:9dff94b1bed5af738655d4a7cbcdcde2bd503aa85c94334fe1f42af7f3dd5ee3
       model_name: gpt-4
       prompt:
           "Please provide a concrete and realistic test case as a dictionary for function invocation using the ** operator.
@@ -18,7 +19,7 @@ dataset:
         name: headline_generation_for_business
         parameters:
           tech_startup_business: str
-      number_of_examples: 1
+      number_of_examples: 2
       output_path: null
   source_type: machine_generated
 
@@ -31,8 +32,9 @@ variations:
         variation_id: null
     generator_name: openai_prompt_based_variation_generator
     generator_config:
-      openai_model_name: gpt-4
-      number_of_variations: 1
+     #model_name specify the llm model , e.g. a16z-infra/llama-2-13b-chat:9dff94b1bed5af738655d4a7cbcdcde2bd503aa85c94334fe1f42af7f3dd5ee3
+      model_name: gpt-4
+      number_of_variations: 2
       diversify: true
       variables: null
       prompt: 
@@ -65,6 +67,7 @@ evaluators:
       D It meets the criterion very well.
       E It meets the criterion exceptionally well, with little to no room for improvement.
     choices: ["A", "B", "C", "D", "E"]
+    # model_name specify the llm model , e.g. a16z-infra/llama-2-13b-chat:9dff94b1bed5af738655d4a7cbcdcde2bd503aa85c94334fe1f42af7f3dd5ee3
     model_name: gpt-4
     description: "evaluate the quality of the landing page headline"
     scale_description: "0-4"
diff --git a/src/yival/schemas/varation_generator_configs.py b/src/yival/schemas/varation_generator_configs.py
index 562b2734..f841dbe9 100644
--- a/src/yival/schemas/varation_generator_configs.py
+++ b/src/yival/schemas/varation_generator_configs.py
@@ -20,7 +20,7 @@ class OpenAIPromptBasedVariationGeneratorConfig(BaseVariationGeneratorConfig):
     """
     Generate variation using chatgpt. Currently only support openai models.
     """
-    openai_model_name: str = "gpt-4"
+    model_name: str = "gpt-4"
     prompt: Union[str, List[Dict[str, str]]] = ""
     diversify: bool = False
     variables: Optional[List[str]] = None
diff --git a/src/yival/variation_generators/openai_prompt_based_variation_generator.py b/src/yival/variation_generators/openai_prompt_based_variation_generator.py
index bbe85071..eb658668 100644
--- a/src/yival/variation_generators/openai_prompt_based_variation_generator.py
+++ b/src/yival/variation_generators/openai_prompt_based_variation_generator.py
@@ -3,11 +3,12 @@
 import pickle
 from typing import Any, Dict, Iterator, List
 
-import openai
 from tqdm import tqdm
 
 from ..common import utils
+from ..common.model_utils import llm_completion
 from ..schemas.experiment_config import WrapperVariation
+from ..schemas.model_configs import Request
 from ..schemas.varation_generator_configs import (
     OpenAIPromptBasedVariationGeneratorConfig,
 )
@@ -109,7 +110,7 @@ def generate_variations(self) -> Iterator[List[WrapperVariation]]:
                     responses = asyncio.run(
                         utils.parallel_completions(
                             message_batches,
-                            self.config.openai_model_name,
+                            self.config.model_name,
                             self.config.max_tokens,
                             pbar=pbar
                         )
@@ -131,13 +132,17 @@ def generate_variations(self) -> Iterator[List[WrapperVariation]]:
                     desc="Generating Variations",
                     unit="variation"
                 ) as pbar:
-                    output = openai.ChatCompletion.create(
-                        model=self.config.openai_model_name,
-                        messages=messages,
-                        temperature=1,
-                        presence_penalty=1,
-                        max_tokens=self.config.max_tokens,
-                    )
+                    output = llm_completion(
+                        Request(
+                            model_name=self.config.model_name,
+                            prompt=messages,
+                            params={
+                                "temperature": 1,
+                                "presence_penalty": 1,
+                                "max_tokens": self.config.max_tokens,
+                            }
+                        )
+                    ).output
                     if self.config.variables and not validate_output(
                         output.choices[0].message.content,
                         self.config.variables