In the system of multi-inverters connected with the grid, the impedance of the grid will cause a coupling between inverters. The coupling effect of the inverters makes it complex to analyze the resonant characteristics of the multiple grid-tied inverters, especially between inverters of the different type. An increasing number of parallel converters makes the coupling effect more serious. Based on this, a method of decoupling and simplifying the coupling effect of multi-inverters is proposed. First, the output current of the inverter is separated and the resonance characteristics of each part are analyzed. Then, the relationship between the interaction current resonance of the multiple grid-tied inverters and the overall current harmonic oscillation of the network is obtained. Finally, a simulation model is built on the Matlab/Simulink platform, and the correctness of the conclusion is verified by simulation.