好像是很老的问题了，但还是要问

Question

DateTimePicker1.Format = DateTimePickerFormat.Short;ms-help://MS.MSDNQTR.2003FEB.2052/cpref/html/frlrfsystemwindowsformsdatetimepickerformatclasstopic.htm

Answer 1

dtp.Value=Convert.ToDateTime("2003-02-01"); 
不是这样么

Answer 2

DateTime.Parse("2003-12-11 11:34:25").ToShortDateString()

Answer 3

DateTime.Parse(DateTimePicker1.Value).ToString("yyyy-MM-dd");

Answer 4

可以将Format属性设成Custom，再CustomFormat属性进行自定义定制
要不就是把得到的时间截下来，只用前面的

Answer 5

是格式的话如下
public void CreateMyDateTimePicker()
{
   // Create a new DateTimePicker control and initialize it.
   DateTimePicker dateTimePicker1 = new DateTimePicker();   // Set the MinDate and MaxDate.
   dateTimePicker1.MinDate = new DateTime(1985, 6, 20);
   dateTimePicker1.MaxDate = DateTime.Today;   // Set the CustomFormat string.
   dateTimePicker1.CustomFormat = "MMMM dd, yyyy - dddd";
   dateTimePicker1.Format = DateTimePickerFormat.Custom;   // Show the CheckBox and display the control as an up-down control.
   dateTimePicker1.ShowCheckBox = true;
   dateTimePicker1.ShowUpDown = true;
}