Abstract: The paper put forward a scheme of harmonic compensation for power system with active power filter(APF).Taking paralleled active power filter as investigated subject,it made systematic study for topology,detection algorithm of compensation reference,control strategies of the APF.On the basis of the study,it introduced the design of paralleled APF based on DSP.It verified the validity and practicability of the mathematic model,detection algorithm and control strategies of the APF by simulation experiment.