Abstract: Aiming at the air gap balancing problem of hybrid-excitation double primary linear motor (HEDPLM) for ropeless hoisting in long stroke operation, and considering the coupling effect of air gap adjustment magnetic field and load angle and uncertain disturbance, we establish a mathematical model of the air gap balancing system, and propose an improved sliding mode active disturbance rejection air gap balancing controller. Firstly, we improve the Levant differentiator by using the continuous function, which reduces the output chattering of the reference signal. Secondly, we design a new sliding mode reaching law, introduce it into the feedback control loop, and then prove the stability of the control system using the Lyapunov theory. The simulation results verify that the designed new sliding mode controller is robust and improves the system response speed under the above conditions.