尝试：

 Process.Start（ @  C：\ Users \trainee7 \Desktop\ConsoleApplication2 \ConsoleApplication2 \bin\Debug\ConsoleApplication2.exe ，
 @  C：\ Users \trainee7 \Desktop\\\
otepads \\ \\ec2.txt跨度>）; 

When I write
"C:\Users\trainee7\Desktop\ConsoleApplication2\ConsoleApplication2\bin\Debug\ConsoleApplication2.exe C:\Users\trainee7\Desktop\notepads\ec2.txt"
in my cmd it will execute.
"C:\Users\trainee7\Desktop\ConsoleApplication2\ConsoleApplication2\bin\Debug\ConsoleApplication2.exe" is for open notepad files.
but my

Process.Start(@"C:\Users\trainee7\Desktop\ConsoleApplication2\ConsoleApplication2\bin\Debug\ConsoleApplication2.exe C:\Users\trainee7\Desktop\notepads\ec2.txt");

arise filenotexception
How can solve it?

Try:

Process.Start(@"C:\Users\trainee7\Desktop\ConsoleApplication2\ConsoleApplication2\bin\Debug\ConsoleApplication2.exe", 
              @"C:\Users\trainee7\Desktop\notepads\ec2.txt");