我找到了解决方案。此代码适用于Windows 10：

Option Explicit

#If VBA7 Then

'// 64 Bits

'// Declarações DLL para alterar ou aparência do UserForm

Private Declare PtrSafe Function FindWindow Lib "user32" Alias "FindWindowA" (ByVal lpClassName As String, ByVal lpWindowName As String) As Long

Private Declare PtrSafe Function GetWindowLong Lib "user32" Alias "GetWindowLongA" (ByVal hwnd As Long, ByVal nIndex As Long) As Long

Private Declare PtrSafe Function SetWindowLong Lib "user32" Alias "SetWindowLongA" (ByVal hwnd As Long, ByVal nIndex As Long, ByVal dwNewLong As Long) As Long

Private Declare PtrSafe Function DrawMenuBar Lib "user32" (ByVal hwnd As Long) As Long

Private Declare PtrSafe Function SetLayeredWindowAttributes Lib "user32" (ByVal hwnd As Long, ByVal crKey As Long, ByVal bAlpha As Byte, ByVal dwFlags As Long) As Long

#Else

'// 32 Bits

'// Declarações DLL para alterar ou aparência do UserForm

Private Declare Function FindWindow Lib "user32" Alias "FindWindowA" (ByVal lpClassName As String, ByVal lpWindowName As String) As Long

Private Declare Function GetWindowLong Lib "user32" Alias "GetWindowLongA" (ByVal hwnd As Long, ByVal nIndex As Long) As Long

Private Declare Function SetWindowLong Lib "user32" Alias "SetWindowLongA" (ByVal hwnd As Long, ByVal nIndex As Long, ByVal dwNewLong As Long) As Long

Private Declare Function DrawMenuBar Lib "user32" (ByVal hwnd As Long) As Long

Private Declare Function SetLayeredWindowAttributes Lib "user32" (ByVal hwnd As Long, ByVal crKey As Long, ByVal bAlpha As Byte, ByVal dwFlags As Long) As Long

#End If

'// Constantes windows para barra de título

Private Const GWL_STYLE As Long = (-16)           '//The offset of a window's style

Private Const GWL_EXSTYLE As Long = (-20)         '//The offset of a window's extended style

Private Const WS_CAPTION As Long = &HC00000       '//Style to add a titlebar

Private Const WS_EX_DLGMODALFRAME As Long = &H1   '//Controls if the window has an icon
 
'// Constantes windows para transparência

Private Const WS_EX_LAYERED = &H80000             '//color

Private Const LWA_COLORKEY = &H1                  '//Chroma key for fading a certain color on your Form

Private Const LWA_ALPHA = &H2                     '//Only needed if you want to fade the entire userform

Function HideTitleBarAndBordar(frm As Object)

'// Hide TitleBar and UserForm Border

    Dim lngWindow As Long

    Dim lFrmHdl As Long

    lFrmHdl = FindWindow(vbNullString, frm.Caption)

    
'// Build window and set window until you remove the caption, title bar and frame around the window

    lngWindow = GetWindowLong(lFrmHdl, GWL_STYLE)

    lngWindow = lngWindow And (Not WS_CAPTION)

    SetWindowLong lFrmHdl, GWL_STYLE, lngWindow

    lngWindow = GetWindowLong(lFrmHdl, GWL_EXSTYLE)

    lngWindow = lngWindow And Not WS_EX_DLGMODALFRAME

    SetWindowLong lFrmHdl, GWL_EXSTYLE, lngWindow

    DrawMenuBar lFrmHdl

End Function

Function MakeUserformTransparent(frm As Object, Optional Color As Variant)

'//set transparencies on userform***********************************

Dim formhandle As Long

Dim bytOpacity As Byte

formhandle = FindWindow(vbNullString, frm.Caption)

If IsMissing(Color) Then Color = &H8000&        '//rgbWhite

bytOpacity = 0

SetWindowLong formhandle, GWL_EXSTYLE, GetWindowLong(formhandle, GWL_EXSTYLE) Or WS_EX_LAYERED

frm.BackColor = Color

SetLayeredWindowAttributes formhandle, Color, bytOpacity, LWA_COLORKEY

End Function