diff --git a/YLErpDAL/Modules/UnderlyingModule/UnderlyingHelper.cs b/YLErpDAL/Modules/UnderlyingModule/UnderlyingHelper.cs
index 17936953..48fb0846 100644
--- a/YLErpDAL/Modules/UnderlyingModule/UnderlyingHelper.cs
+++ b/YLErpDAL/Modules/UnderlyingModule/UnderlyingHelper.cs
@@ -253,43 +253,22 @@ namespace YLErp.Modules.UnderlyingModule
         /// <returns>返回3.12格式</returns>
         public static double? getYearTerm(DateTime? calcDate, DateTime? sourceDate)
         {
-            if (!calcDate.HasValue)
+            if (!calcDate.HasValue || !sourceDate.HasValue)
+                return null;
+
+            if (calcDate.Value > sourceDate.Value)
+                throw new ArgumentException("计算日期必须小于原日期", nameof(calcDate));
+
+            int totalMonths = (sourceDate.Value.Year - calcDate.Value.Year) * 12
+                            + (sourceDate.Value.Month - calcDate.Value.Month);
+
+            if (sourceDate.Value.Day < calcDate.Value.Day)
             {
-                return null;//不限
+                totalMonths--;
             }
-            if (sourceDate.HasValue)
-            {
-                if (calcDate > sourceDate)
-                {
-                    throw new ArgumentException("计算日期必须小于原日期", nameof(calcDate));
-                }
-                //计算sourceDate与calcDate年限差
-                int yearDiff = sourceDate.Value.Year - calcDate.Value.Year;
-                int monthDiff = sourceDate.Value.Month - calcDate.Value.Month;
-                int dayDiff = sourceDate.Value.Day - calcDate.Value.Day;
 
-                // 如果月差为负，说明还没到整年，需要向前借一年
-                if (monthDiff < 0)
-                {
-                    yearDiff -= 1;
-                    monthDiff += 12;
-                }
-
-                // 如果天数为负，说明还没到整月，需要向前借一个月
-                if (dayDiff < 0)
-                {
-                    monthDiff -= 1;
-                    if (monthDiff < 0)
-                    {
-                        yearDiff -= 1;
-                        monthDiff += 12;
-                    }
-                }
-
-                double yearTerm = yearDiff + monthDiff / 12.0;
-                return yearTerm;
-            }
-            return null;//不限
+            double yearTerm = totalMonths / 12.0;
+            return yearTerm;
         }
         /// <summary>
         /// 根据标的发行年限和剩余期限计算适用保证金率