diff --git a/apps/desktop/src-tauri/src/infrastructure/gemini_service.rs b/apps/desktop/src-tauri/src/infrastructure/gemini_service.rs
index b6f41e3..196d631 100644
--- a/apps/desktop/src-tauri/src/infrastructure/gemini_service.rs
+++ b/apps/desktop/src-tauri/src/infrastructure/gemini_service.rs
@@ -1108,17 +1108,18 @@ impl GeminiService {
                     conversation_context.history_included = true;
 
                     // 添加系统提示（如果有）
-                    if let Some(system_prompt) = &request.system_prompt {
-                        contents.push(ContentPart {
-                            role: "system".to_string(),
-                            parts: vec![Part::Text { text: system_prompt.clone() }],
-                        });
+                    let system_prompt = if let Some(system_prompt) = &request.system_prompt {
+                        system_prompt.clone()
                     } else if let Some(default_prompt) = &rag_config.system_prompt {
-                        contents.push(ContentPart {
-                            role: "system".to_string(),
-                            parts: vec![Part::Text { text: default_prompt.clone() }],
-                        });
-                    }
+                        default_prompt.clone()
+                    } else {
+                        return Err(anyhow::anyhow!("系统提示词不能为空，请在请求中提供 system_prompt 或在配置中设置默认 system_prompt"));
+                    };
+
+                    contents.push(ContentPart {
+                        role: "system".to_string(),
+                        parts: vec![Part::Text { text: system_prompt }],
+                    });
 
                     // 添加历史消息
                     for msg in &history_messages {