Hi Kedaman, I just add the GetClassName API function ontop of you code & it work. The only think is the GetClassNAme API return me the PictureBox Class Name = "ThunderPictureBoxDC" instead of "ThunderPictureBox" Anyway, I manage to differentiate between the PictureBox and others control.

Now, I have the handle for 2 different picture box, but how do I differentiate the handle is belong to which PictureBox.

Code:
Private Declare Function EnumChildWindows Lib "user32" (ByVal hWndParent As Long, ByVal lpEnumFunc As Long, ByVal lParam As Long) As Long
Private Declare Function GetParent Lib "user32" (ByVal hwnd As Long) As Long
Private Declare Function GetClassName Lib "user32" Alias "GetClassNameA" (ByVal hwnd As Long, ByVal lpClassName As String, ByVal nMaxCount As Long) As Long
Private Declare Function SetParent Lib "user32" (ByVal hWndChild As Long, ByVal hWndNewParent As Long) As Long

Private returnval(), counter%, Parent&
Private ReturnStr$, nReturn&, rethWnd$
Private PichWnd(), hWndCnt%
Private Function EnumFunction(ByVal hwnd&, ByVal lParam&) As Long
    'If Parent = GetDesktopWindow Then
    'If GetParent(hwnd) <> Parent Then If GetParent(hwnd) > 0 Then EnumFunction = True: Exit Function  'Exits if it's a indirect child
    'Else
    If GetParent(hwnd) <> Parent Then EnumFunction = True: Exit Function 'Exits if it's a indirect child
    'End If
    counter = counter + 1
    ReDim Preserve returnval(counter - 1)
    returnval(counter - 1) = hwnd
    
    ReturnStr = String(255, Chr(0))
    nReturn = GetClassName(hwnd, ReturnStr, 255)
    If nReturn <> 0 Then
        rethWnd = Left(ReturnStr, InStr(1, ReturnStr, Chr(0), vbBinaryCompare) - 1)
        If rethWnd = "ThunderPictureBoxDC" Then
            hWndCnt = hWndCnt + 1
            ReDim Preserve PichWnd(hWndCnt)
            PichWnd(hWndCnt) = hwnd
        End If
    End If
    EnumFunction = True
End Function

Public Function Getchild(Parenthwnd&)
    Parent = Parenthwnd
    counter = 0
    hWndCnt = 0
    EnumChildWindows Parenthwnd, AddressOf EnumFunction, 0
    If counter Then Getchild = returnval
    SetParent PichWnd(1), PichWnd(2)
End Function