在子窗體寫構造函數，然後再在父窗體按鈕點擊事件下寫

 public frmIDW(AxMapControl axMapControl1)
        {
            InitializeComponent();
            this.axMapControl1 = axMapControl1;
        }
        private AxMapControl axMapControl1;

private void Krige_ItemClick(object sender, ItemClickEventArgs e)
        {
            Krige krige = new Krige( axMapControl1);
            krige.Visible = true;
        }

AE二次開發，解決子窗體使用父窗體的AxControl控件