Abstract: For problem that using PI controller to control active power filter can not realize floating control because of harmonic or fundamental current, and digitization will further increase steady-state error, so lead to reduce compensation performance of active power filter，a control strategy of active disturbance rejection control was proposed. The strategy uses nonlinear tracking differentiator and extended state observer of the active disturbance rejection controller to process reference input and output, and selects appropriate state error to achieve automatic and accurate filter compensation. The simulation and experiment results prove the filter has strong robustness, stability and adaptability, and improves control performance with the active disturbance rejection control strategy.