A three-phase DC link active power filter (APF)based on coupled impedance and its control strategy are proposed in order to eliminate the input current harmonics of the three-phase diode rectifier. The presented APF is composed of impedance network and two asymmetric dual Boost converters. Average current control is adopted to control the DC link APF. The switch signals of the two asymmetric Boost converters are obtained respectively by leading and trailing edge modulation methods. Compared with the normal DC link active power filter,this topology reduces an active switch and a capacitance. So it can reduce costs,and there is no voltage imbalance in the DC link. Simulation results verify the correctness of the proposed topology and the corresponding control method.