The linear active disturbance rejection control (LADRC) is widely used in permanent magnet synchronous linear motors (PMSLM) due to its simple structure,easy implementation and strong anti-interference ability.However,the motor start-up and load mutation will lead to the decrease of the disturbance estimation accuracy of linear extended state observer (LESO) in LADRC system.Therefore,a PMSLM fractional order active disturbance rejection control based on time-variable gain nonlinear extended state observer (TNESO) was proposed.Combining LESO with nonlinear disturbance observer (NDOB),a dynamic gain function was constructed according to the relationship between error and gain,and a new state observer TNESO was designed;on this basis,the fractional order PDμcontrol law was used to replace the linear state error feedback control law (LSEF),and an improved active disturbance rejection speed control system was established,to further improve the real-time and robustness of motor control.The simulation and experimental results show that the designed speed control system can effectively reduce the observation response time when the linear motor starts and the load changes suddenly,and suppress the disturbance peak at the initial observation time,so as to meet the high-performance PMSLM speed control requirements.