When I run my program in VS2010, because my output quite a lot,the console just discards my previous output.
For example, consider my output to be of 400 lines, line
Right before your output. You can set it dynamically based on output but be sure to remember that if a line is longer than the width you will have additional lines to contend with.
Console.BufferHeight = x;
Console.BufferWidth = x;
Sets the height and width of the console buffer.
You can change the buffering settings of the console: right click the title bar of the console window and select "Properties." On the "Layout" tab, change the "Height" of the Screen Buffer to some large number (9999, for example).
Run your program again.
Of course, if you have a large amount of output that you need to inspect on a regular basis, it's probably best to write to a file instead.