diff --git a/UefiCpuPkg/Include/Library/CpuPageTableLib.h b/UefiCpuPkg/Include/Library/CpuPageTableLib.h
index 6225a1d8e974..cd493ad69ccb 100644
--- a/UefiCpuPkg/Include/Library/CpuPageTableLib.h
+++ b/UefiCpuPkg/Include/Library/CpuPageTableLib.h
@@ -67,6 +67,7 @@ typedef enum {
   Create or update page table to map [LinearAddress, LinearAddress + Length) with specified attribute.
 
   @param[in, out] PageTable      The pointer to the page table to update, or pointer to NULL if a new page table is to be created.
+                                 If not pointer to NULL, the value it points to won't be changed in this function.
   @param[in]      PagingMode     The paging mode.
   @param[in]      Buffer         The free buffer to be used for page table creation/updating.
   @param[in, out] BufferSize     The buffer size.
diff --git a/UefiCpuPkg/Library/CpuPageTableLib/CpuPageTableMap.c b/UefiCpuPkg/Library/CpuPageTableLib/CpuPageTableMap.c
index ae4caf8dfe60..7c2bd25d22a6 100644
--- a/UefiCpuPkg/Library/CpuPageTableLib/CpuPageTableMap.c
+++ b/UefiCpuPkg/Library/CpuPageTableLib/CpuPageTableMap.c
@@ -640,6 +640,7 @@ PageTableLibMapInLevel (
   Create or update page table to map [LinearAddress, LinearAddress + Length) with specified attribute.
 
   @param[in, out] PageTable      The pointer to the page table to update, or pointer to NULL if a new page table is to be created.
+                                 If not pointer to NULL, the value it points to won't be changed in this function.
   @param[in]      PagingMode     The paging mode.
   @param[in]      Buffer         The free buffer to be used for page table creation/updating.
   @param[in, out] BufferSize     The buffer size.