public MainWindow() { InitializeComponent(); var data = new List <HocSinh> { new HocSinh { MSSV = 20172605, Name = "Le Quang Huy" }, new HocSinh { MSSV = 20172538, Name = "Nguyen Thi Hien" }, }; var sp = new StackPanel { Background = Brushes.AliceBlue, Orientation = Orientation.Horizontal, }; var mcb = new MyComboBox(); foreach (var item in data) { var mcbi = new MyComboBoxItem(item, "Name", "MSSV"); mcb.Add(mcbi); } var bt = new Button { Content = "Submit", Width = 50, Height = 25, }; bt.Click += (s, e) => { MessageBox.Show(mcb.SelectedItem.ReturnValue.ToString()); }; sp.Children.Add(mcb); sp.Children.Add(bt); Content = sp; }