When the current source PWM rectifier is at the operate condition that the grid voltage is unbalanced, the negative sequence component of grid voltage will cause low-frequency pulsation in DC side and low-order harmonics in grid side current. To solve this problem, the resonance control with the inner DC current loop based on the traditional double closed loop with active damping is applied in this article to directly suppress low-frequency pulsation existed in the DC side outputs, and the sinusoidal current at the grid side is formed. Besides, the current of the filter capacitor as the compensation term is added into the current reference value on the grid side. In this case, current and voltage with the same phase are realized on the grid side. Furthermore, to improve the operating performance of the system under extremely unbalance conditions, a notch filter is introduced in the modulation link to eliminate low-order harmonic components, which improves the current waveform on grid side. Finally, simulation test is studied by using MATLAB/ Simulink and a 3 kW prototype is established. The simulation and experimental results indicate that when the unbalance degree of the grid reach 6. 7% and 20% , the proposed control strategy can effectively suppress the voltage fluctuation on DC side within 1. 2 V, and the total harmonic distortion rate on the grid side current is less than 4% .