diff --git a/HybirdFrameworkCore/Utils/BitUtls.cs b/HybirdFrameworkCore/Utils/BitUtls.cs
index 8c4f63a..15337a2 100644
--- a/HybirdFrameworkCore/Utils/BitUtls.cs
+++ b/HybirdFrameworkCore/Utils/BitUtls.cs
@@ -61,7 +61,7 @@ public static class BitUtls
         {
             length = length / 8;
             var bt = new byte[length];
-
+            start = start / 8;
             for (var i = start; i < start + length; i++) bt[i - start] = bytes[i];
 
             return bt;