I have a project to characterize some mosfet and obtain the switching characteristic of those mosfet. I need to build a board to do that. I have build a half-bridge and inductive-load test circuit and record some data. But I don't know what further I should do, hopefully someone can give a direction to me . Thank you.

 

This is reinventing the wheel. All you need to do is look up the data sheet on any device and you get that measurement, plus the circuit used to obtain it. As an example, look up the IRF6610 and you'll see.