diff --git a/NetworkPkg/WifiConnectionManagerDxe/WifiConnectionMgrImpl.c b/NetworkPkg/WifiConnectionManagerDxe/WifiConnectionMgrImpl.c
index 2e596c1981..d1182e52bd 100644
--- a/NetworkPkg/WifiConnectionManagerDxe/WifiConnectionMgrImpl.c
+++ b/NetworkPkg/WifiConnectionManagerDxe/WifiConnectionMgrImpl.c
@@ -572,15 +572,28 @@ WifiMgrConfigEap (
   // Set Identity to Eap peer, Mandatory field for PEAP and TTLS
   //
   if (StrLen (Profile->EapIdentity) > 0) {
-    IdentitySize = sizeof (CHAR8) * (StrLen (Profile->EapIdentity) + 1);
-    Identity     = AllocateZeroPool (IdentitySize);
+    Status = gBS->LocateProtocol (&gEdkiiWiFiProfileSyncProtocolGuid, NULL, (VOID **)&WiFiProfileSyncProtocol);
+    if (!EFI_ERROR (Status)) {
+      //
+      // Max size of EapIdentity ::= sizeof (CHAR16) * sizeof (Profile->EapIdentity) ::= 2 * EAP_IDENTITY_SIZE
+      //
+      IdentitySize = sizeof (CHAR8) * (AsciiStrnLenS ((CHAR8 *)Profile->EapIdentity, sizeof (CHAR16) * sizeof (Profile->EapIdentity)) + 1);
+    } else {
+      IdentitySize = sizeof (CHAR8) * (StrLen (Profile->EapIdentity) + 1);
+    }
+
+    Identity = AllocateZeroPool (IdentitySize);
     if (Identity == NULL) {
       return EFI_OUT_OF_RESOURCES;
     }
 
-    Status = gBS->LocateProtocol (&gEdkiiWiFiProfileSyncProtocolGuid, NULL, (VOID **)&WiFiProfileSyncProtocol);
     if (!EFI_ERROR (Status)) {
-      CopyMem (Identity, &Profile->EapIdentity, IdentitySize);
+      //
+      // The size of Identity from Username may equal
+      // to the max size of EapIdentity(EAP_IDENTITY_SIZE*2=128 bytes),
+      // so here only valid characters except NULL characters are copied.
+      //
+      CopyMem (Identity, &Profile->EapIdentity, IdentitySize - 1);
     } else {
       UnicodeStrToAsciiStrS (Profile->EapIdentity, Identity, IdentitySize);
     }