添加'/'字符后，TEdit.CaretPosition属性仍在当前位置，即字符的左侧。更新CaretPosition以将插入符号移动到字符的右侧，例如：

procedure TForm1.Edit1ChangeTracking(Sender: TObject);
begin
  if (Edit1.Text.Length = 2) then
  begin
    Edit1.Text := Edit1.Text + '/';
    Edit1.CaretPosition := Edit1.Text.Length;
    // or: Edit1.GoToTextEnd();
  end;
end;

Tom Brunberg正确地识别出代码属于OnTyping事件处理程序，而不是OnChangeTracking。我遇到的一个后续错误是用户不能退格到“/”后面来更正错误（因为每次他们删除“/”，都会自动插入一个新的）。下面是我用来修复该错误并获得完全预期效果的完整代码：
WriteExpiry是一个TEEdit。

procedure TForm1.WriteExpiryTyping(Sender: TObject);
begin

//INSERTS A '/' AFTER THE FIRST TWO DIGITS OF THE EXPIRY DATE
 if (WriteExpiry.Text.Length = 2) then
 begin
 WriteExpiry.Text := WriteExpiry.Text + '/';
 WriteExpiry.CaretPosition := WriteExpiry.Text.Length;
 end;

//PROTECTS AGAINST USER TYPING '/' THEMSELVES AND CREATING '//'
 if (WriteExpiry.Text.Length = 4)then
 begin
 if WriteExpiry.Text[4] = '/' then
  begin
  WriteExpiry.Text := WriteExpiry.Text[1] + WriteExpiry.Text[2] + WriteExpiry.Text[3];
  WriteExpiry.CaretPosition := WriteExpiry.Text.Length;
   end;
 end;

procedure TForm1.WriteExpiryKeyDown(Sender: TObject; var Key: Word;
  var KeyChar: Char; Shift: TShiftState);
begin
//ALLOWS THE USER TO BACKSPACE PAST THE INSERTED '/'
if (Key = vkBack) and (WriteExpiry.Text.Length = 3) then
  begin
  WriteExpiry.Text := WriteExpiry.Text[1] + WriteExpiry.Text[2];
  WriteExpiry.CaretPosition := WriteExpiry.Text.Length;
  end;
end;