Abstract: In order to solve the problem of grid-connected resonance of unilateral parallel energy storage converter, the resonance mechanism is analyzed, and the suppression method is designed. By studying the amplitude and phase parameters of the system under standby and operating conditions, the resonance characteristics are obtained. The resonance causes are divided into internal and external causes. The internal cause is that the output current of the parallel system is superimposed with the parallel machine, and the harmonic voltage drop is generated on the grid-connected impedance, resulting in voltage harmonic amplification. The external cause is that the background voltage harmonics contained on the grid side overlap with the impedance frequency of the parallel system in some frequency bands. With the increase of the random number, the frequency of the system resonance point will decrease. The designed voltage harmonic compensation unit is used for power decoupling and the dynamic multi-proportional resonant controller is used for control decoupling to achieve resonance suppression. The mechanism of resonance and the effectiveness of the suppression method are verified by simulation.