I need to open a excel in web browser when click a button.how to do that in asp.net
You can't control and launch software on the client (browser) computer - why? Security.
If this was possible, hackers would have taken over all computers long ago...
Can you please explain exactly what you are trying to do? Instead of asking how to open excel from the browser, if you explain what you need to accomplish, perhaps we can come up with a better idea.