diff --git a/Src/Asp.NetCore2/SqlSugar/Realization/Oracle/SqlBuilder/OracleExpressionContext.cs b/Src/Asp.NetCore2/SqlSugar/Realization/Oracle/SqlBuilder/OracleExpressionContext.cs
index 6ff97e560..e50b8c561 100644
--- a/Src/Asp.NetCore2/SqlSugar/Realization/Oracle/SqlBuilder/OracleExpressionContext.cs
+++ b/Src/Asp.NetCore2/SqlSugar/Realization/Oracle/SqlBuilder/OracleExpressionContext.cs
@@ -391,7 +391,7 @@ namespace SqlSugar
         {
             var parameterNameA = mode.Args[0].MemberName;
             var parameterNameB = mode.Args[1].MemberName;
-            return $" SUBSTR({parameterNameA}, -2, {parameterNameB})  ";
+            return $" SUBSTR({parameterNameA}, (LENGTH({parameterNameA})-2), {parameterNameB})  ";
         }
 
         public override string Ceil(MethodCallExpressionModel mode)