Dhaval247寫的
https://social.msdn.microsoft.com/Forums/vstudio/en-US/85e61265-db47-451c-aa9e-6e2f67d88783/how-to-set-default-value-in-datagridview-textbox-column-vbnet?forum=vbgeneral

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load Dim column3 As New DataGridViewTextBoxColumn DataGridView1.Columns.Add(column3) column3.Width = 80 column3.Name = ("QTY") End Sub Private Sub DataGridView1_DefaultValuesNeeded(ByVal sender As Object, ByVal e As System.Windows.Forms.DataGridViewRowEventArgs) Handles DataGridView1.DefaultValuesNeeded e.Row.Cells("QTY").Value = "100" End Sub
上面有試過，應是可以。
他是預先設定一個值，輸入新值後就改過舊值。