This paper presents an adaptive control strategy, for realizing the maximum power point tracking (MPPT), applicable to the wind energy generation system with direct-driven permanent magnet synchronous generators (PMSG). Disturbance, caused by the generator torque loss and the uncertainty of one-mass shaft model parameters, exists in the system. To obtain an optimal electromagnetic torque overcoming the disturbance, an adaptive control law is proposed based on Lyapunov stability. Simulations prove the proposed strategy coordinates the contradiction between overshoot and quick response of tracking. The rotor speed tracks the optimal rotor speed accurately, even though the system loss is changing and the wind speed profile is varying.