I have just install VB.NET, I want to write a software to interface with peripheral via USB port. Now could you list for me some helpful functions for that work ? (for e.g read data from USB port or write data to it ...)
I will do research on them, thanks so much :)

Do you want to read raw data or interface with a driver or api? Either way, this is not a simple task. To read raw data you would have to write your own driver to interface with USB devices. Look at http://www.osdev.org/wiki/USB for assistance.