方法一（Reflection）：

Dim str As String
str = "myTest.Form2"  '必须是 命名空间+点+窗体类名
Dim tempAssembly As System.Reflection.Assembly = System.Reflection.Assembly.GetExecutingAssembly()
Dim frm2 As Form = CType(tempAssembly.CreateInstance(str), Form)
frm2.Show()

方法二（Type.GetType() ）：

Dim frmName, fullName As String
frmName = "form2"
fullName = Application.ProductName & "." & frmName
Dim frm2 As Form
frm2 = Activator.CreateInstance(Type.GetType(fullName, True, True))
frm2 .Visible = True