In order to study the wake flow of 3D rotating rotor, this paper numerically simulated the wake of a given fan by using moving reference frame （MRF）. The velocity and pressure distribution of wake flow field under different inlet wind velocity and pitch angles were studied for wind turbine generator. It is found that the influences of wind field velocity, pressure distribution, wake, inlet wind velocity and pitch angles changes on the whole flow field are consistent with the actual situation. This method can forecast the running performance and wake turbulence of wind turbine, and achieve the simulation of the aerodynamic flow field of wind turbine. Using numerical simulation method to replace part of model machine experiments can shorten the experiment time, save the experiment cost, shorten the development cycle, and can provide reliable suggestions for the operation of units.