I have an object that I'm trying to bind its properties to two DateTimePicker controls.

class Order
{
  public DateTime OrderPlacedDate { get; }
  public Nullable<DateTime> ShippedDate { get; }
}

What is the proper way to bind Nullable DateTime Property to DateTimePicker?

There's not really a right way since the DateTimePicker does not have good support for null values. You have a couple of options:

1. You can use a ReadOnly TextBox and a MonthCalendar rather than a DateTimePicker. You'd bind to the TextBox and use the MonthCalendar to set the date in the TextBox.

2. You can use DateTimePicker's null support which is a little clumsy from a UI perspective. This also requires you to write some glue code that maps the DateTimePicker's null representation to a null on your Nullable<DateTime> property. You can do this as follows:

Customer _customer; // Has a Nullable<DateTime> property called "HireDate"

private void Form1_Load(object sender, EventArgs e)
{
    // Create Customer
    _customer = new Customer("555", "John Doe", 1000, DateTime.Now);

    // Bind
    Binding binding = new Binding("Value", _customer, "HireDate", true);
    this.dateTimePicker1.DataBindings.Add(binding);

    // BindingComplete
    binding.Format += new ConvertEventHandler(Binding_Format);
    binding.Parse += new ConvertEventHandler(Binding_Parse);
}

void Binding_Parse(object sender, ConvertEventArgs e)
{
    // Need to make the Control show NULL
    Binding binding = sender as Binding;

    if (null != binding)
    {
        DateTimePicker dtp = (binding.Control as DateTimePicker);

        if ((null != dtp) && (dtp.Checked))
            e.Value = new Nullable<DateTime>();
    }
}

void Binding_Format(object sender, ConvertEventArgs e)
{
    INullableValue inv = (e.Value as INullableValue);

    if ((null != inv) && (!inv.HasValue))
    {
        // Need to make the Control show NULL
        Binding binding = sender as Binding;

        if (null != binding)
        {
            DateTimePicker dtp = (binding.Control as DateTimePicker);

            if (null != dtp)
            {
                dtp.ShowCheckBox = true;
                dtp.Checked = false;
                e.Value = dtp.Value;
            }
        }
    }
}