一、从文件加载

 Private Sub Button1_Click(ByVal sender As System.Object,ByVal e As System.EventArgs) Handles Button1.Click
        Dim strFilename1 As String
        Dim Pic1 As System.Drawing.Image
        strFilename1 = "c:\1.png"
        Pic1 = System.Drawing.Image.FromFile(strFilename1)
        PictureBox1.SizeMode = PictureBoxSizeMode.StretchImage

        'PictureBox1.Image = Pic1

        Dim Pic2 As System.Drawing.Image
        Dim strFilename2 As String = "c:\2.png "
        Pic2 = System.Drawing.Image.FromFile(strFilename2)


        Dim b As New System.Drawing.Bitmap(Pic2.Width,Pic2.Height,PixelFormat.Format32bppArgb)  '这个地方是做透明处理结果的
        Dim g As Graphics = Graphics.FromImage(b)
        g.Clear(Color.Transparent)

        g.DrawImage(Pic2,New Rectangle(0,Pic2.Width,Pic2.Height),GraphicsUnit.Pixel)
        g.DrawImage(Pic1,Pic1.Width,Pic1.Height),GraphicsUnit.Pixel)


        PictureBox1.Image = b
        PictureBox1.BackColor = Color.Transparent

        'b.Save("c:\3.png")

    End Sub

  '从资源文件中加载
    Private Sub Button2_Click(ByVal sender As System.Object,ByVal e As System.EventArgs) Handles Button2.Click

        Dim Pic1 As System.Drawing.Image
        Pic1 = My.Resources._1

        Dim Pic2 As System.Drawing.Image
        Pic2 = My.Resources._2


        Dim b As New System.Drawing.Bitmap(Pic2.Width,PixelFormat.Format32bppArgb) '这个地方是做透明处理结果的
        Dim g As Graphics = Graphics.FromImage(b)
        g.Clear(Color.Transparent)

        g.DrawImage(Pic2,GraphicsUnit.Pixel)


        PictureBox1.Image = b
        PictureBox1.BackColor = Color.Transparent  '这个地方是做透明处理结果的
        PictureBox1.SizeMode = PictureBoxSizeMode.StretchImage

        ' b.Save("c:\3.png")

    End Sub