diff --git a/Learn.Archives.API/Controllers/StudentController.cs b/Learn.Archives.API/Controllers/StudentController.cs
index 1435f77..c3f6dad 100644
--- a/Learn.Archives.API/Controllers/StudentController.cs
+++ b/Learn.Archives.API/Controllers/StudentController.cs
@@ -98,8 +98,8 @@ namespace Learn.Archives.API.Controllers
                 if (!exDataDic.ContainsKey(item.Id)) continue;
                 var ex = exDataDic[item.Id].First();
                 item.Status = ex.Status;
-                item.ExitTime = ex.ExitTime?.ToString("yyyy-MM-dd")??string.Empty;
-                item.JoinTime = ex.JoinTime?.ToString("yyyy-MM-dd") ?? string.Empty;
+                item.ExitTime = ex.ExitTime==null? string.Empty : ex.ExitTime?.ToString("yyyy-MM-dd");
+                item.JoinTime = ex.JoinTime == null ? string.Empty : ex.JoinTime?.ToString("yyyy-MM-dd");
 
                 item.AmountRelief = ex.AmountRelief;
                 item.ReliefApplication = ex.ReliefApplication;
diff --git a/Learn.Archives.Core/Model/Student.cs b/Learn.Archives.Core/Model/Student.cs
index 08ba783..67900ac 100644
--- a/Learn.Archives.Core/Model/Student.cs
+++ b/Learn.Archives.Core/Model/Student.cs
@@ -64,13 +64,13 @@ namespace Learn.Archives.Core.Model
         /// 退出时间
         /// </summary>
         [SugarColumn(IsNullable = true)]
-        public DateTime? ExitTime { get; set; } = DateTime.Now;
+        public DateTime? ExitTime { get; set; } 
 
         /// <summary>
         /// 退出时间
         /// </summary>
         [SugarColumn(IsNullable = true)]
-        public DateTime? JoinTime { get; set; } = DateTime.Now;
+        public DateTime? JoinTime { get; set; }
 
         /// <summary>
         /// 创建时间