直接添加一个MID父窗体或在已有窗体的属性中找到IsMDIContainer属性，然后设置为True，然后创建第二个窗体 ，需要加载子窗体的时候：
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Dim NewMDIChild As New Form2
NewMDIChild.MdiParent = Me
NewMDIChild.Show()
Public Shared Sub CheckMDIChildForm(ByVal MDIForm As Windows.Forms.Form, ByVal MDIChildForm As Windows.Forms.Form, ByVal MDIChildFormName As String)
If MDIForm.MdiChildren.Length 1 Then
'如果没有任何一个MDI子窗体，则创该MDI子窗体的窗体实例
Dim MDIChildFrm As Windows.Forms.Form = MDIChildForm ' 定义MDI子窗体
MDIChildFrm.MdiParent = MDIForm '指定父窗体
MDIChildFrm.Show() '打开窗体
Exit Sub
Else
Dim x As Integer
Dim frmyn As Boolean
For x = 0 To (MDIForm.MdiChildren.Length) - 1
Dim tempChild As Windows.Forms.Form = CType(MDIForm.MdiChildren(x), Windows.Forms.Form)
If tempChild.Name = MDIChildFormName Then
'检测到有该MDI子窗体，设为激活 并退出循环
frmyn = True
tempChild.BringToFront()
Exit For
Else
frmyn = False
End If
Next
If Not frmyn Then
'在打开的窗体中没检测到则新建
Dim MDIChildFrm As Windows.Forms.Form = MDIChildForm ' 定义MDI子窗体
MDIChildFrm.MdiParent = MDIForm '指定父窗体
MDIChildFrm.Show() '打开窗体
End If
End If
End Sub
qufulin750说的对
使用showdialog方法就行了，一般的show方法可以操作主窗体
你把代码写在 Activated 事件中试验一下，写在 Load 事件中肯定不能隐藏form1窗体。
Private Sub Form1_Activated(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Activated
Me.Hide()
Form2.Show()
End Sub
至于一关闭form1整个程序就会关闭，是因为你的form1是主窗体，你找到Application.Designer.vb这个文件，默认应该都有，这里面有这样的代码
Global.System.Diagnostics.DebuggerStepThroughAttribute() _
Protected Overrides Sub OnCreateMainForm()
Me.MainForm = Global.WindowsApplication1.Form1
End Sub
从代码Me.MainForm = Global.WindowsApplication1.Form1中可以看出Form1()是主窗体，如果你想改变主窗体，那么只要修改对应的Form。
加以一个panel用来显示应用程序的，就是放你那个easycap的，代码如下
Declare Function SetParent Lib "user32" Alias "SetParent" (ByVal hWndChild As IntPtr, ByVal hWndNewParent As IntPtr) As Integer
Declare Function FindWindow Lib "user32" Alias "FindWindowA" (ByVal lpClassName As String, ByVal lpWindowName As String) As IntPtr
Private Declare Function SendMessage Lib "user32.dll" Alias "SendMessageA" (ByVal hwnd As Int32, ByVal wMsg As Int32, ByVal wParam As Int32, ByVal lParam As Int32) As Int32
Private Declare Function ShellExecute Lib "shell32.dll" Alias "ShellExecuteA" (ByVal hwnd As Int32, ByVal lpOperation As String, ByVal lpFile As String, ByVal lpParameters As String, ByVal lpDirectory As String, ByVal nShowCmd As Int32) As Int32
Private Const WM_SYSCOMMAND As Int32 = H112
Private Const SC_MAXIMIZE As Int32 = HF030
Private Const SC_MINIMIZE As Int32 = HF020
Private Const SC_RESTORE As Int32 = HF120
Public Const SW_HIDE = 0
Public Const SW_SHOW = 5
Private Declare Function ShowWindow Lib "user32.dll" (ByVal hwnd As Int32, ByVal nCmdShow As Int32) As Int32
Private Sub Button1_Click_1(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
ShellExecute(Me.Panel1.Handle, "open", "c:\windows\system32\cmd.exe", Nothing, ".", SW_HIDE)
System.Threading.Thread.Sleep(50)
Dim h As IntPtr = FindWindow(Nothing, "c:\windows\system32\cmd.exe")
ShowWindow(h, SW_HIDE)
SetParent(h, Me.Panel1.Handle) '嵌到panel1内
SendMessage(h, WM_SYSCOMMAND, SC_MAXIMIZE, 0)
End Sub
把其中的c:\windows\system32\cmd.exe换成你要嵌入的应用程序
