Abstract: This paper analyzes the working principle and operating characteristic of brushless doubly fed wind power generator(BDFG),and deduces the BDFG's mathematical model based on rotor machine coordinate,The variable structure control(VSC) is applied to the active and reactive power decoupling control of the BDFM,analysis and the relations of electromagnetism and energy balance are analyzed.Finally,simulation and analysis of the whole system and control strategy are carried out in Matlab/Simulink software.Simulation results show that the VSC method can not only realize the active and reactive power decoupling control of the BDFM to obtain the maximum wind power capture,but also adjust the reactive power of the electric grid to satisfy the requirements of the electric power system.