When designing the drive circuit of power MOSFET, the influence of parasitic parameters on the circuit should be concerned. As an important parameter of MOSFET device, Miller capacitance should be considered in the design of drive circuit. The variation of gate voltage, drain source voltage and drain source current during the turnon and turnoff of MOSFET were observed. The influences of parasitic parameters such as Miller capacitance and parasitic inductance on drain source voltage and drain source current were analyzed. The reasons of gate voltage oscillation nearby Miller plateau were analyzed, and the restraining measures were put forward. This research was instructive for the drive design of power MOSFET.