Abstract: To improve the speed control performance of the permanent magnet synchronous motor (PMSM) drive system and to solve the conflict between jitter and speed of the traditional sliding mode control system, an improved sliding mode composite control scheme for PMSM is proposed. Firstly, the current loop is designed with an improving fast super twisting algorithm (IFSTA) to improve the system jitter. Secondly, the speed loop uses an improved exponential convergence law to design the novel sliding mode speed controller (NSMSC). Finally, a nonlinear extended state observer (NESO) to estimate the load torque disturbance in real time and feed-forward compensates the q-axis given current obtained from the NSMSC by the estimated torque information. It is shown by simulation and experiment that the improved composite control strategy reduces the overshoot by 13.6% compared with the conventional sliding mode composite control, reduces the system jitter peak by 3.5 r/min, and improves the overall performance of the control system.