To optimize the operation efficiency of the large-scale variable-speed constant-frequency（VSCF） wind power generation system above the rated wind speed， an adaptive gain-schedule linear-quadratic-Gaussian（AGS-LQG） control strategy is proposed on the basis of effective mean wind speed estimation with the extended Kalman filter. The effective mean wind speed is as the scheduling variable to achieve adaptive gain schedule of controller parameters， so the controller can operate well even though the operation point changes. The proposed AGS-LQG control strategy can realize multi-variable integrated optimal control for the large-scale VSCF wind power generation system. Simulation results on a 1.5 MW VSCF wind power generator show that， on condition of large-scale variable wind speed， the AGS-LQG control strategy can not only make the wind turbine rotate speed more stable to smooth the generator's output power， but also reduce the action frequency of pitch-controlled equipment to alleviate the mechanical load of transmission chain. The method has great significance on the improvement of power quality and prolonging service life of facilities.