diff --git a/app/controllers/borrow.py b/app/controllers/borrow.py
index 250d169..75348ae 100644
--- a/app/controllers/borrow.py
+++ b/app/controllers/borrow.py
@@ -22,6 +22,16 @@ def borrow_book():
         flash('请选择要借阅的图书', 'danger')
         return redirect(url_for('book.book_list'))
 
+    # 检查用户当前借阅数量是否达到上限(5本)
+    current_borrows_count = BorrowRecord.query.filter_by(
+        user_id=current_user.id,
+        status=1  # 1表示借阅中
+    ).count()
+
+    if current_borrows_count >= 5:
+        flash('您当前已借阅5本图书，达到借阅上限。请先归还后再借阅新书。', 'warning')
+        return redirect(url_for('book.book_detail', book_id=book_id))
+
     book = Book.query.get_or_404(book_id)
 
     # 检查库存
@@ -101,6 +111,18 @@ def add_borrow(book_id):
     # 验证图书存在
     book = Book.query.get_or_404(book_id)
 
+    # 检查用户当前借阅数量是否达到上限(5本)
+    current_borrows_count = BorrowRecord.query.filter_by(
+        user_id=current_user.id,
+        status=1  # 1表示借阅中
+    ).count()
+
+    if current_borrows_count >= 5:
+        return jsonify({
+            'success': False,
+            'message': '您当前已借阅5本图书，达到借阅上限。请先归还后再借阅新书。'
+        })
+
     # 默认借阅天数
     borrow_days = 14
 
diff --git a/app/controllers/inventory.py b/app/controllers/inventory.py
index 83e5dab..f641102 100644
--- a/app/controllers/inventory.py
+++ b/app/controllers/inventory.py
@@ -60,7 +60,7 @@ def inventory_list():
 
 @inventory_bp.route('/adjust/<int:book_id>', methods=['GET', 'POST'])
 @login_required
-@permission_required('manage_inventory')  # 替代 @admin_required
+@permission_required('manage_inventory')
 def adjust_inventory(book_id):
     """调整图书库存"""
     book = Book.query.get_or_404(book_id)
diff --git a/app/controllers/statistics.py b/app/controllers/statistics.py
index dc388f0..c5c849d 100644
--- a/app/controllers/statistics.py
+++ b/app/controllers/statistics.py
@@ -118,6 +118,8 @@ def api_borrow_trend():
     """获取借阅趋势数据API"""
     time_range = request.args.get('time_range', 'month')
 
+    now = datetime.now()
+
     # 记录获取借阅趋势数据的日志
     Log.add_log(
         action="获取数据",
@@ -150,8 +152,8 @@ def api_borrow_trend():
 
             # 当天逾期未还的数量
             overdue_count = BorrowRecord.query.filter(
-                BorrowRecord.due_date < day_end,
-                BorrowRecord.return_date.is_(None)
+                BorrowRecord.return_date.is_(None),  # 未归还
+                BorrowRecord.due_date < now  # 应还日期早于当前时间
             ).count()
 
             results.append({
@@ -186,9 +188,10 @@ def api_borrow_trend():
             ).count()
 
             # 当天逾期未还的数量
+            now = datetime.now()
             overdue_count = BorrowRecord.query.filter(
-                BorrowRecord.due_date < day_end,
-                BorrowRecord.return_date.is_(None)
+                BorrowRecord.return_date.is_(None),
+                BorrowRecord.due_date < now
             ).count()
 
             results.append({
@@ -231,9 +234,10 @@ def api_borrow_trend():
             ).count()
 
             # 当月逾期未还的数量
+            now = datetime.now()
             overdue_count = BorrowRecord.query.filter(
-                BorrowRecord.due_date < month_end,
-                BorrowRecord.return_date.is_(None)
+                BorrowRecord.return_date.is_(None),
+                BorrowRecord.due_date < now
             ).count()
 
             results.append({