diff --git a/service/src/chatgpt/index.ts b/service/src/chatgpt/index.ts
index 3ade78d..fc25bd2 100644
--- a/service/src/chatgpt/index.ts
+++ b/service/src/chatgpt/index.ts
@@ -45,6 +45,19 @@ let api: ChatGPTAPI | ChatGPTUnofficialProxyAPI
       debug: true,
     }
 
+    // increase max token limit if use gpt-4
+    if (model.toLowerCase().includes('gpt-4')) {
+      // if use 32k model
+      if (model.toLowerCase().includes('32k')) {
+        options.maxModelTokens = 32768
+        options.maxResponseTokens = 8192
+      }
+      else {
+        options.maxModelTokens = 8192
+        options.maxResponseTokens = 2048
+      }
+    }
+
     if (isNotEmptyString(OPENAI_API_BASE_URL))
       options.apiBaseUrl = `${OPENAI_API_BASE_URL}/v1`