The permanent magnet synchronous generator (PMSG) is investigated and its mathematical model is established in two-phase synchronous rotating coordinates. Aiming at the fact that PMSG may present chaotic behaviors at certain values of parameters and under certain working conditions, the output feedback control gain matrix with the minimum performance index is obtained by solving the Riccatic equation and fed back to the system in order to improve the system performance with considering the disturbance. Results show that the optimal output feedback H∞ control based on Riccatic equation can respond to PMSG very quickly and accurately in the chaotic state when disturbance occurs.