In this paper, an improved Sliding Mode Control(SMC) is proposed based on the Wind Energy Conversion System(WECS), which is with offshore wind turbine Permanent Magnet Synchronous Generator(PMSG) connected to the grid. Moreover, an aerodynamic torque observer is presented to improve the performance of Maximum Power Point Tracking(MPPT). Since the wind energy conversion system is a complicated nonlinear system, an enhanced reach law of sliding mode controller is designed to reduce the chattering issue. Compared to traditional control methods, the simulation results show that the control method proposed in this paper significantly improves the stability and robustness of PMSG-Based WECS in the area of MPPT. (C) 2020 Elsevier Ltd. All rights reserved.