In view of problem of bad stability of wind energy conversion system based on linear constant controller caused by stochastic volatility of wind speed, the paper proposed a design scheme of wind energy conversion system of permanent magnet synchronous generator based on sliding-mode control. It analyzed building principle of model of wind turbine, model of driving device and model of permanent magnet synchronous generator in the system , and introduced implementation of sliding-mode control strategy. The simulation result shows that the system has good speed tracking characteristic to realize maximum wind energy capturing.