But it seems not  work well. I set the defaultcellvalue in InitializeLayout ,and when a button click for call SetDataBinding. when DefaultCellValue = False ,it works well ,but when DefaultCellValue = True , it is not ok, it always show the False state. it is my test code.  by the way , when I set the column datatype as string , it is not work well yet.

    Private Sub UltraGrid1_InitializeLayout(ByVal sender As Object, ByVal e As Infragistics.Win.UltraWinGrid.InitializeLayoutEventArgs) Handles UltraGrid1.InitializeLayout

        UltraGrid1.DisplayLayout.AddNewBox.Hidden = False

        With e.Layout.Bands(0)
            If Not .Columns.Exists("COL1") Then
                .Columns.Add("COL1")
                .Columns("COL1").DataType = GetType(Boolean)
                .Columns("COL1").DefaultCellValue = True
            End If
            If Not .Columns.Exists("COL2") Then
                .Columns.Add("COL2")
                .Columns("COL2").DataType = GetType(String)
            End If
        End With
    End Sub

    Private Sub UltraButton1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles UltraButton1.Click
        UltraGrid1.SuspendLayout()

        Dim dt As New DataTable
        Dim dr As DataRow
        dt.Columns.Add("COL2", GetType(String))
        For i As Integer = 0 To 9
            dr = dt.NewRow
            dr.Item("COL2") = CStr(i + 4)
            dt.Rows.Add(dr)
        Next
        dt.AcceptChanges()
        UltraGrid1.SetDataBinding(dt, Nothing, True)

    End Sub