diff --git a/MdeModulePkg/Universal/DriverSampleDxe/NVDataStruc.h b/MdeModulePkg/Universal/DriverSampleDxe/NVDataStruc.h
index 40fb3d0964..6f092de8b6 100644
--- a/MdeModulePkg/Universal/DriverSampleDxe/NVDataStruc.h
+++ b/MdeModulePkg/Universal/DriverSampleDxe/NVDataStruc.h
@@ -35,6 +35,14 @@ Revision History:
 
 #pragma pack(1)
 
+//
+// !!! For a structure with a series of bit fields and used as a storage in vfr file, and if the bit fields do not add up to the size of the defined type.
+// In the C code use sizeof() to get the size the strucure, the results may vary form the compiler(VS,GCC...).
+// But the size of the storage calculated by VfrCompiler is fixed (calculate with alignment).
+// To avoid above case, we need to make the total bit width in the structure aligned with the size of the defined type for these bit fields. We can:
+// 1. Add bit field (with/without name) with remianing with for padding.
+// 2. Add unnamed bit field with 0 for padding, the amount of padding is determined by the alignment characteristics of the members of the structure.
+//
 typedef struct {
   UINT16   NestByteField;
   UINT8                    : 1;  // unamed field can be used for padding
@@ -84,7 +92,9 @@ typedef struct {
   UINT8   Match2;
   UINT8   GetDefaultValueFromCallBackForOrderedList[3];
   UINT8   BitCheckbox : 1;
+  UINT8   ReservedBits: 7;  // Reserved bit fields for padding.
   UINT16  BitOneof    : 6;
+  UINT16              : 0;  // Width 0 used to force alignment.
   UINT16  BitNumeric  : 12;
   MY_BITS_DATA  MyBitData;
   MY_EFI_UNION_DATA MyUnionData;
@@ -109,6 +119,7 @@ typedef struct {
   UINT32   EfiBitNumeric     : 4;
   UINT32   EfiBitOneof       : 10;
   UINT32   EfiBitCheckbox    : 1;
+  UINT32                     : 0;  // Width 0 used to force alignment.
 } MY_EFI_BITS_VARSTORE_DATA;
 
 //