1 namespace Test
 2 {
 3     public partial class FrmMain : Form
 4     {
 5         public FrmMain()
 6         {
 7              InitializeComponent();
 8         }
 9         public DataTable DT;
10         private void button1_Click(object sender, EventArgs e) 
11         { 
12             FrmChild fm = new FrmOptime(this); 
13             fm.Show(); 
14          } 
15         public void BindData(){}
16      }
17 }

主窗体

 1 namespace Test
 2 {
 3     public partial class FrmChild : Form
 4     {
 5         public FrmChild ()
 6         {
 7             InitializeComponent();
 8         }
 9         FrmMain frmMain;
10         public FrmChild (FrmMain fm)
11         {
12             InitializeComponent();
13             frmMain = fm;
14         }
15     private void button1_Click(object sender, EventArgs e) 
16     { 
17         frmMain.RemnantDT;
18         frmMain.BindData();
19     }
20    }
21 }

子窗体