Abstract: In order to make the active power filter (APF) can fast and precisely output compensation harmonic, this paper presented an improved deadbeat control algorithm based on repetitive prediction principle for APF's main circuit. This paper firstly introduced the working principle of the parallel active power filter, secondly established the mathematical model of the three-phase shunt active power filter and analyzed deadbeat control principle according to mathematical model. Finally it is known that harmonic instruction current signal prediction is the key to determining the deadbeat control effect, through the deadbeat control principle. In order to improve APF's filtering effect with the deadbeat control method, the improved repetitive prediction strategy was employed to predict the next beat output current according to the harmonic periodicity, and its stability was analyzed. This improved repetitive predictive deadbeat control strategy can improve the steady precision and transient response speed. Simulation waveform analysis and experimental results analysis proved the feasibility of the control strategy.