A novel speed and flux estimation method of permanent magnet synchronous motor(PMSM) for sensorless vector control based on Robust Extended Kalman Filter(REKF) is proposed in this paper. The effect of gross error on estimation accuracy of Extended Kalman Filter (EKF) is analyzed. The model of PMSM based on REKF is established, and whether REKF can give better estimation performance than EKF is discussed when PMSM is disturbed by gross error. The speed estimation error and the flux change coursed by external gross error and internal estimation gross error based on REKF are compared with EKF. REKF has better performance against gross error than EKF, and the system can converge faster when disturbed. The simulation results verify the validity of the proposed speed and flux estimation method based on Robust Extended Kalman Filter.