// String to DateTime
 String MyString;
 MyString = "1999-09-01 21:34 PM";
 //MyString = "1999-09-01 21:34 p.m.";  //Depends on your regional settings

 DateTime MyDateTime;
 MyDateTime = new DateTime();
 MyDateTime = DateTime.ParseExact(MyString, "yyyy-MM-dd HH:mm tt", null);

资料来源： http://www.codeproject.com/KB/cs/String2DateTime.aspx

修改为适合您的日期格式：

Modified to fit your date format:

 // String to DateTime
 String MyString;
 MyString = "Jun 17 2009, 03:37 pm";

 DateTime MyDateTime;
 MyDateTime = new DateTime();
 MyDateTime = DateTime.ParseExact(MyString, "MMM dd YYYY, HH:mm tt", null);