For PWM modulation method of the active power filter,simplified three-level space voltage vector modulation algorithm based on two level has been adopted in this paper. The conventional three-level space voltage vector modulation algorithm and the simplified algorithm are separately analyzed. By comparing the two algorithms, it is found that the obtained function time and basic function vector of them are exactly the same, so it is shown that the simplified algorithm can not only make the computation simple, but also achieve the same output characteristic to the conventional algorithm. The simulation test is a further indication of the effectiveness of the simplified method.