The maximum wind energy capture of the variable-speed constant-frequency wind turbine driven doubly-fed induction generator（DFIG） is studied based on aerodynamic torque and wind speed estimation. After an analysis of wind turbine's characteristics and basic electromagnetic relationship of DFIG， the nonlinear mathematical model of the wind generation system is established. Then the feedback linearization theory is used to design a nonlinear controller. The nonlinear controller has two output variables: the d -axis and q -axis components of rotor voltage. The q -axis component is used to maximize the wind energy capture by forcing the wind turbine to stay close to the optimal rotor speed. The d -axis component is used to minimize the copper losses by regulating the reactive power of DFIG. Simulation results prove the correctness and feasibility of the proposed control strategy.