diff --git a/exam_pkg/api.py b/exam_pkg/api.py
index d05f3e9..623c90d 100644
--- a/exam_pkg/api.py
+++ b/exam_pkg/api.py
@@ -29,7 +29,7 @@ from auth.gateway import (
 )
 
 # 导入统一响应格式
-from core.status_codes import EXAM_SUCCESS, GRADE_SUCCESS, EXAM_ERROR, GRADE_ERROR, BAD_REQUEST, NO_CONTENT, LLM_ERROR
+from core.status_codes import EXAM_SUCCESS, GRADE_SUCCESS, EXAM_ERROR, GRADE_ERROR, BAD_REQUEST, UNAUTHORIZED, FORBIDDEN, NO_CONTENT, LLM_ERROR
 from api.response_utils import success_response, error_response
 
 # 合法题型
@@ -152,13 +152,14 @@ def api_generate_questions():
         if diff_error:
             return error_response("INVALID_PARAMS", BAD_REQUEST, diff_error, http_status=400)
 
-        # 校验总题数上限
-        MAX_TOTAL_QUESTIONS = 20
+        # 校验总题数（不设上限，但提醒用户大量出题可能影响性能）
         total_requested = sum(question_types.values())
-        if total_requested > MAX_TOTAL_QUESTIONS:
+        if total_requested <= 0:
             return error_response("INVALID_PARAMS", BAD_REQUEST,
-                f"总题数不能超过 {MAX_TOTAL_QUESTIONS} 道，当前请求 {total_requested} 道",
+                "总题数必须大于0",
                 http_status=400)
+        if total_requested > 50:
+            logger.warning(f"[出题] 请求生成 {total_requested} 道题，可能影响性能")
 
         # 校验排除题干列表（可选）
         exclude_stems = data.get('exclude_stems')
@@ -169,7 +170,7 @@ def api_generate_questions():
         # 获取当前用户
         user = get_current_user()
         if not user:
-            return error_response("UNAUTHORIZED", BAD_REQUEST, "未认证", http_status=401)
+            return error_response("UNAUTHORIZED", UNAUTHORIZED, "未认证", http_status=401)
 
         # 检查向量库访问权限
         if not check_collection_permission(
@@ -178,9 +179,9 @@ def api_generate_questions():
             collection_name=collection,
             operation="read"
         ):
-            return error_response("FORBIDDEN", BAD_REQUEST, "权限不足", http_status=403)
+            return error_response("FORBIDDEN", FORBIDDEN, "权限不足", http_status=403)
 
-        # 调用新版出题接口
+        # 调用新版出题接口（同步）
         result = generate_questions_from_file(
             file_path=file_path,
             collection=collection,
@@ -251,7 +252,7 @@ def api_generate_smart():
         # 获取当前用户
         user = get_current_user()
         if not user:
-            return error_response("UNAUTHORIZED", BAD_REQUEST, "未认证", http_status=401)
+            return error_response("UNAUTHORIZED", UNAUTHORIZED, "未认证", http_status=401)
 
         # 检查向量库访问权限
         if not check_collection_permission(
@@ -260,7 +261,7 @@ def api_generate_smart():
             collection_name=collection,
             operation="read"
         ):
-            return error_response("FORBIDDEN", BAD_REQUEST, "权限不足", http_status=403)
+            return error_response("FORBIDDEN", FORBIDDEN, "权限不足", http_status=403)
 
         # 1. 调用 AI 分析文件，获取推荐的题型和数量
         from exam_pkg.manager import analyze_file_for_exam
diff --git a/exam_pkg/generator.py b/exam_pkg/generator.py
index eda54c6..7b3d5e4 100644
--- a/exam_pkg/generator.py
+++ b/exam_pkg/generator.py
@@ -1055,7 +1055,7 @@ def analyze_document_for_exam(chunks: List[Dict], max_total: int = None) -> Dict
 
 注意：
 - 不适合的题型数量设为 0
-- 所有数量之和不要超过 {min(total_knowledge_points * 2, 20)}
+- 所有数量之和不要超过 {min(total_knowledge_points * 2, max_total if max_total else 20)}
 - 必须返回合法 JSON，不要有其他内容
 
 请直接输出 JSON："""
diff --git a/exam_pkg/grader.py b/exam_pkg/grader.py
index 18f0e1b..e4bd05b 100644
--- a/exam_pkg/grader.py
+++ b/exam_pkg/grader.py
@@ -219,6 +219,29 @@ def grade_fill_blank(answer: Dict) -> Dict:
     student_answers = answer.get('student_answer', [])
     max_score = answer.get('max_score', 4.0)
 
+    # 校验学生答案格式（必须是列表）
+    if not isinstance(student_answers, list):
+        logger.warning(f"填空题学生答案格式错误: 期望列表，实际为 {type(student_answers).__name__}: {student_answers}")
+        return {
+            "question_id": answer.get('question_id'),
+            "score": 0,
+            "max_score": max_score,
+            "grading_status": "failed",
+            "details": {"error": f"学生答案格式错误，期望列表，实际为 {type(student_answers).__name__}"}
+        }
+
+    # 校验学生答案列表中的每个元素必须是字符串
+    for i, ans in enumerate(student_answers):
+        if not isinstance(ans, str):
+            logger.warning(f"填空题学生答案第 {i+1} 项格式错误: 期望字符串，实际为 {type(ans).__name__}: {ans}")
+            return {
+                "question_id": answer.get('question_id'),
+                "score": 0,
+                "max_score": max_score,
+                "grading_status": "failed",
+                "details": {"error": f"填空题学生答案第 {i+1} 项格式错误，期望字符串，实际为 {type(ans).__name__}"}
+            }
+
     # 归一化答案格式（修复 LLM 生成的扁平数组问题）
     blank_count = question_content.get('data', {}).get('blank_count', 0)
     correct_answers = _normalize_fill_blank_answer(correct_answers, blank_count)