Private Sub DataGrid1_UpdateCommand(ByVal source As Object, ByVal e As System.Web.UI.WebControls.DataGridCommandEventArgs) Handles DataGrid1.UpdateCommand
DataGrid1.EditItemIndex = -1

Dim name1 As TextBox = e.Item.Cells(1).Controls(0)

mycom.Connection = con
con.Open()
myadp.SelectCommand = mycom
mycom.CommandType = CommandType.Text
mycom.CommandText = "update contact set name='" + name1.Text.ToString() + "'"
mycom.ExecuteNonQuery()
con.Close()

End Sub

红色的那句好象不对，应该怎么改，运行时候说“无效的类型转换”

如果它不是textbox类型的话，你也无法强转啊。
我估计你的那个是自定义模板，所以你试试用e.item.cells(1).controls(1)试试。