Abstract: Working principle of three-level paralleling active power filter based on switching function was introduced, mathematical model for the active power filter was established, and a deadbeat control scheme for the active power filter was proposed. In the scheme, ip-iq method is used to detect harmonic current, reference current at the next sampling time is forecasted by use of load current detected at current sampling time and compensated current, and output reference voltage of the active power filter at the next sampling time is calculated. Finally, switch signal of bridge is obtained by use of space voltage vector algorithm to track and control current. The simulation result showed that the three-level paralleling active power filter controlled by the scheme can track and control detected current perfectly, which restrains harmonic effectively and has good dynamic response.