可以透過 Microsoft Jet Replication Objects (JRO) 的 JetEngine.CompactDatabase 方法。

請記得備份原始的 Accdb 檔案。

<pre class="c" name="code">
Public Sub CompactAndEncrypt()
   Dim je As New JRO.JetEngine

   ' Make sure that a file doesn't exist with the name of
   ' the compacted database.
   If Dir("C:\Program Files\Microsoft Office\" & _
      "Office\Samples\Northwind2.mdb") <> "" Then Kill _
      "C:\Program Files\Microsoft Office\Office\Samples\Northwind2.mdb"

   ' Compacts and encrypts version Northwind database.
   je.CompactDatabase _
   "Provider=Microsoft.Jet.OLEDB.4.0;" & _
      "Data Source=C:\Program Files\Microsoft Office\" & _
      "Office\Samples\Northwind.mdb", _
   "Provider=Microsoft.Jet.OLEDB.4.0;" & _
      "Data Source=C:\Program Files\Microsoft Office\" & _
      "Office\Samples\Northwind2.mdb;" & _
   "Jet OLEDB:Encrypt Database=True"

End Sub

參考：
http://msdn.microsoft.com/en-us/library/office/bb213241(v=office.12).aspx
http://msdn.microsoft.com/en-us/library/office/bb237197(v=office.12).aspx