Non-linear loads appear in the power industry on a large scale, and the acquisition of high-quality electric energy has also become a universal problem. Active power filter (APF), which has the advantages of dynamic tracking and better compensation effects, has become the most efficient power electronic device in the field of harmonic pollution control. It has gradually replaced traditional passive filters and achieved rapid development. This paper first describes the basic principles of APF, the main circuit topology. The specific detection method based on the theory of instantaneous reactive power design was selected, PI control was used as the control strategy of this design, and SPWM was selected as the control method of this design. Through the analysis of the results of the Matlab/Simulink simulation, it can be concluded that the active power filter can suppress harmonics in real time.