diff --git a/src/TelegramPanel.Core/Services/AccountRiskService.cs b/src/TelegramPanel.Core/Services/AccountRiskService.cs
index 95774ee..01e8074 100644
--- a/src/TelegramPanel.Core/Services/AccountRiskService.cs
+++ b/src/TelegramPanel.Core/Services/AccountRiskService.cs
@@ -17,9 +17,12 @@ public class AccountRiskService
     /// </summary>
     public RiskCheckResult CheckLoginDuration(Account account)
     {
-        if (account.LastLoginAt == null)
+        var referenceAt = account.GetRiskReferenceAtUtc();
+        var loginHours = account.GetRiskReferenceHours();
+
+        if (referenceAt == null || loginHours == null)
         {
-            // 无登录记录，视为高风险（刚导入的账号）
+            // 兜底：完全缺少可参考的时间，视为高风险
             return new RiskCheckResult
             {
                 IsRisky = true,
@@ -28,16 +31,30 @@ public class AccountRiskService
             };
         }
 
-        var loginHours = (DateTime.UtcNow - account.LastLoginAt.Value).TotalHours;
-
-        if (loginHours < RISK_THRESHOLD_HOURS)
+        // 兼容历史数据：LastLoginAt 为空时，使用导入时间（CreatedAt）作为估算，避免永久误报
+        var isEstimated = account.IsRiskReferenceEstimated();
+        if (isEstimated && loginHours >= RISK_THRESHOLD_HOURS)
         {
-            var remainingHours = RISK_THRESHOLD_HOURS - loginHours;
+            return new RiskCheckResult
+            {
+                IsRisky = false,
+                Message = "账号登录时长已满足要求（按导入时间估算）",
+                DetailedMessage = $"当前已导入时长：{loginHours.Value:F1} 小时"
+            };
+        }
+
+        if (loginHours.Value < RISK_THRESHOLD_HOURS)
+        {
+            var remainingHours = RISK_THRESHOLD_HOURS - loginHours.Value;
             return new RiskCheckResult
             {
                 IsRisky = true,
-                Message = $"账号登录时长不足 24 小时（当前：{loginHours:F1} 小时）",
-                DetailedMessage = $"建议等待 {remainingHours:F1} 小时后再进行敏感操作，以降低被 Telegram 风控的风险"
+                Message = isEstimated
+                    ? $"账号未记录登录时间（按导入时间估算：{loginHours.Value:F1} 小时）"
+                    : $"账号登录时长不足 24 小时（当前：{loginHours.Value:F1} 小时）",
+                DetailedMessage = isEstimated
+                    ? $"该账号尚未记录登录时间（可能是较早导入的账号），已按导入时间估算；建议等待 {remainingHours:F1} 小时后再进行敏感操作，以降低被 Telegram 风控的风险"
+                    : $"建议等待 {remainingHours:F1} 小时后再进行敏感操作，以降低被 Telegram 风控的风险"
             };
         }
 
@@ -45,7 +62,7 @@ public class AccountRiskService
         {
             IsRisky = false,
             Message = "账号登录时长已满足要求",
-            DetailedMessage = $"当前登录时长：{loginHours:F1} 小时"
+            DetailedMessage = $"当前登录时长：{loginHours.Value:F1} 小时"
         };
     }
 
@@ -145,8 +162,12 @@ public class BatchRiskCheckResult
 
         var riskyPhones = string.Join("、", RiskyAccounts.Select(a =>
         {
-            var hours = a.GetLoginHours();
-            return hours.HasValue ? $"{a.Phone}({hours.Value:F1}h)" : a.Phone;
+            var hours = a.GetRiskReferenceHours();
+            if (!hours.HasValue)
+                return a.Phone;
+
+            var tag = a.IsRiskReferenceEstimated() ? "导入" : "登录";
+            return $"{a.Phone}({tag}{hours.Value:F1}h)";
         }));
 
         return $"以下账号登录时长不足 24 小时：{riskyPhones}";
diff --git a/src/TelegramPanel.Data/Entities/AccountExtensions.cs b/src/TelegramPanel.Data/Entities/AccountExtensions.cs
index 8785fca..f2efc28 100644
--- a/src/TelegramPanel.Data/Entities/AccountExtensions.cs
+++ b/src/TelegramPanel.Data/Entities/AccountExtensions.cs
@@ -5,6 +5,42 @@ namespace TelegramPanel.Data.Entities;
 /// </summary>
 public static class AccountExtensions
 {
+    /// <summary>
+    /// 获取风控检查用的参考时间（优先 LastLoginAt，其次 CreatedAt/LastSyncAt 作为估算兜底）
+    /// </summary>
+    public static DateTime? GetRiskReferenceAtUtc(this Account account)
+    {
+        if (account.LastLoginAt != null)
+            return account.LastLoginAt.Value;
+
+        // 兼容历史数据：早期导入的账号可能没有写入 LastLoginAt
+        if (account.CreatedAt != default)
+            return account.CreatedAt;
+
+        if (account.LastSyncAt != default)
+            return account.LastSyncAt;
+
+        return null;
+    }
+
+    /// <summary>
+    /// 风控参考时间是否为估算值（非真实登录时间）
+    /// </summary>
+    public static bool IsRiskReferenceEstimated(this Account account)
+        => account.LastLoginAt == null && account.GetRiskReferenceAtUtc() != null;
+
+    /// <summary>
+    /// 获取风控检查用的参考小时数
+    /// </summary>
+    public static double? GetRiskReferenceHours(this Account account)
+    {
+        var at = account.GetRiskReferenceAtUtc();
+        if (at == null)
+            return null;
+
+        return (DateTime.UtcNow - at.Value).TotalHours;
+    }
+
     /// <summary>
     /// 获取登录小时数的格式化字符串
     /// </summary>
diff --git a/src/TelegramPanel.Web/Components/Pages/AccountLogin.razor b/src/TelegramPanel.Web/Components/Pages/AccountLogin.razor
index 0a7d086..86cdd7a 100644
--- a/src/TelegramPanel.Web/Components/Pages/AccountLogin.razor
+++ b/src/TelegramPanel.Web/Components/Pages/AccountLogin.razor
@@ -354,6 +354,7 @@
                 existingAccount.ApiId = telegramApiId;
                 existingAccount.ApiHash = telegramApiHash;
                 existingAccount.LastSyncAt = DateTime.UtcNow;
+                existingAccount.LastLoginAt = DateTime.UtcNow;
                 await AccountManagement.UpdateAccountAsync(existingAccount);
 
                 Snackbar.Add("账号信息已更新", Severity.Success);
@@ -372,7 +373,8 @@
                     ApiHash = telegramApiHash,
                     IsActive = true,
                     CreatedAt = DateTime.UtcNow,
-                    LastSyncAt = DateTime.UtcNow
+                    LastSyncAt = DateTime.UtcNow,
+                    LastLoginAt = DateTime.UtcNow
                 };
 
                 await AccountManagement.CreateAccountAsync(account);