To address the internal and external disturbances in Permanent Magnet Synchronous Motor (PMSM) such as modeling errors and sudden load variation,a load estimation-based composite Active Disturbance Rejection Control (ADRC) approach is proposed for PMSM speed regulation.ADRC is adopted to replace the PI controller in the speed loop to improve the performance of control system and solve the contradiction between system rapidity and overshooting.A load torque observer is designed to correct the slow response of ESO to sudden load variation by directly estimating and compensating the load torque in real time via speed and current signals.Additionally,a semi-physical experimental platform of composite ADRC for speed regulation is constructed in Matlab/Simulink environment,and the proposed composite ADRC is compared with traditional PI control and linear ADRC.The results illustrate that the proposed approach outperforms conventional controller by reducing the speed variation by more than 30% under abrupt load variation,and has superior disturbance rejection ability and speed regulation performance.