diff --git a/YD_Event.Application/Common/Excel/NpoiExcelReader.cs b/YD_Event.Application/Common/Excel/NpoiExcelReader.cs
index 08f3eb5..8dbb3ff 100644
--- a/YD_Event.Application/Common/Excel/NpoiExcelReader.cs
+++ b/YD_Event.Application/Common/Excel/NpoiExcelReader.cs
@@ -89,14 +89,15 @@ public static class NpoiExcelReader
         }
 
         var result = new List<T>();
-        for (var rowIndex = headerRow.RowNum + 1; rowIndex <= sheet.LastRowNum; rowIndex++)
+        // LastRowNum 会被整表格式残留推到 1048576；只遍历实际存在的行对象。
+        var rowEnumerator = sheet.GetRowEnumerator();
+        while (rowEnumerator.MoveNext())
         {
-            var row = sheet.GetRow(rowIndex);
-            if (row == null) continue;
+            if (rowEnumerator.Current is not IRow row || row.RowNum <= headerRow.RowNum) continue;
 
             var item = new T();
             if (item is IExcelRowLocation rowLocation)
-                rowLocation.ExcelRowNumber = rowIndex + 1;
+                rowLocation.ExcelRowNumber = row.RowNum + 1;
             var hasValue = false;
             foreach (var (columnIndex, property) in columnProperties)
             {
diff --git a/YD_Event.Application/OrderBook/OrderBookService.cs b/YD_Event.Application/OrderBook/OrderBookService.cs
index 6b9aba9..e077f39 100644
--- a/YD_Event.Application/OrderBook/OrderBookService.cs
+++ b/YD_Event.Application/OrderBook/OrderBookService.cs
@@ -506,7 +506,7 @@ public class OrderBookService : IDynamicApiController, ITransient
         return result;
     }
 
-    // 按 项目×组别×场地 生成场次，返回组合键 -> 场次 的映射
+    // 按 项目×组别×场次名称×场地 生成场次，返回组合键 -> 场次 的映射
     private async Task<Dictionary<OrderBookSessionKey, EventSession>> EnsureSessionsAsync(
         OrderBookDraft draft, long eventId,
         Dictionary<long, OrderBookProjectContext> projectContext,
@@ -518,7 +518,22 @@ public class OrderBookService : IDynamicApiController, ITransient
             .Distinct()
             .ToList();
 
+        var existSessions = await _sessionRepository.AsQueryable()
+            .Where(s => !s.DeleteMark && s.EventId == eventId)
+            .ToListAsync();
+        var venueNamesById = venueContext.ToDictionary(x => x.Value.Venue.Id, x => x.Key);
+        var existSessionsByKey = existSessions
+            .Where(s => venueNamesById.ContainsKey(s.VenueId))
+            .GroupBy(s => new OrderBookSessionKey(
+                s.EventProjectId,
+                s.EventProjectGroupId ?? 0,
+                s.SessionName ?? string.Empty,
+                venueNamesById[s.VenueId]))
+            .ToDictionary(x => x.Key, x => x.First());
+
         var result = new Dictionary<OrderBookSessionKey, EventSession>();
+        var newSessions = new List<EventSession>();
+        var usedSessionNos = existSessions.Select(s => s.SessionNo).ToHashSet(StringComparer.Ordinal);
         var sessionSort = 0;
         foreach (var combo in combos)
         {
@@ -526,12 +541,7 @@ public class OrderBookService : IDynamicApiController, ITransient
             var vc = venueContext[combo.VenueName];
             var groupId = combo.EventProjectGroupId;
 
-            var exist = await _sessionRepository.GetFirstAsync(s =>
-                !s.DeleteMark && s.EventId == eventId &&
-                s.EventProjectId == pc.EventProjectId && s.VenueId == vc.Venue.Id &&
-                s.SessionName == combo.SessionName &&
-                s.EventProjectGroupId == groupId);
-            if (exist != null)
+            if (existSessionsByKey.TryGetValue(combo, out var exist))
             {
                 if (exist.ScoreRuleId != pc.ScoreRuleId)
                     throw Oops.Bah($"场次【{combo.SessionName}】的规则与导入项目不一致，请先核查历史编排");
@@ -539,7 +549,13 @@ public class OrderBookService : IDynamicApiController, ITransient
                 continue;
             }
 
-            sessionSort++;
+            string sessionNo;
+            do
+            {
+                sessionSort++;
+                sessionNo = $"EP{pc.EventProjectId}-V{vc.Index:00}-{sessionSort:000}";
+            } while (!usedSessionNos.Add(sessionNo));
+
             var session = new EventSession
             {
                 Id = _idGenerator.NextId(),
@@ -548,7 +564,7 @@ public class OrderBookService : IDynamicApiController, ITransient
                 EventProjectGroupId = groupId,
                 VenueId = vc.Venue.Id,
                 ScoreRuleId = pc.ScoreRuleId,
-                SessionNo = $"EP{pc.EventProjectId}-V{vc.Index:00}-{sessionSort:000}",
+                SessionNo = sessionNo,
                 SessionName = combo.SessionName,
                 SessionStatus = 0,
                 Version = 1,
@@ -556,9 +572,12 @@ public class OrderBookService : IDynamicApiController, ITransient
                 CreatedUserId = userId,
                 CreatedTime = now
             };
-            await _sessionRepository.InsertAsync(session);
+            newSessions.Add(session);
             result[combo] = session;
         }
+
+        if (newSessions.Any())
+            await _sessionRepository.InsertRangeAsync(newSessions);
         return result;
     }