Aiming at the interactive influence problems between inverter side and grid side when a large number of inverters are connected to the utility grid,from the standpoint of external characteristics,output impedance model of three-phase grid-connected inverter with LCL filters based on dual-loop control scheme of grid current and filter capacitor current were firstly proposed and deduced in the synchronous rotating reference frame. Then the feed-forward decoupling control strategy was introduced to eliminate the coupling impedances between the d and q axis control loop. Because the real system would be a digital control system,the control delay was modeled and incorporated into the developed model in order to improve the accuracy of output impedance characteristics. Based on the accurate output impedance model proposed above,the interactive influences and its harmonic resonance mechanism between the multiple inverter systems and the utility grid were modeled and analyzed. Theoretical analysis indicates that the harmonic components form inverter side or grid side will aggravate the grid current distortion in distributed generation system based on multi modules. Simulation results are presented to demonstrate the correctness and effectiveness of the output impedance modeling and system performance analysis method based on distributed interactive network.