您可以通过以下方式使用 System.Diagnostics.Process.Start 以及 WIN32 ShellExecute函数互操作，使用默认浏览器打开PDF文件：

you can use System.Diagnostics.Process.Start as well as WIN32 ShellExecute function by means of interop, for opening PDF files using the default viewer:

System.Diagnostics.Process.Start("SOMEAPP.EXE","Path/SomeFile.Ext");

[System.Runtime.InteropServices.DllImport("shell32. dll")]
private static extern long ShellExecute(Int32 hWnd, string lpOperation, 
                                    string lpFile, string lpParameters, 
                                        string lpDirectory, long nShowCmd);

另一种方法是将一个 WebBrowser控件插入到表单中，然后使用的导航的用于打开PDF文件的方法：

Another approach is to place a WebBrowser Control into your Form and then use the Navigate method for opening the PDF file:

ThewebBrowserControl.Navigate(@"c:\the_file.pdf");