Compared with the traditional power grid, the interconnected system has the advantages of strong power supply flexibility, high equipment utilization, small installed capacity and more economical operation. However, the difference is that when analyzing the stability, the converter dynamic response of the interconnected system is fast. In order to model its internal structure and control, it is necessary to re-establish the model suitable for it. Firstly, three different control types of inverters are modeled, and then starting from the ieee-9 node interconnected system composed of multiple inverters, the system is modeled, and its stability is analyzed through root locus calculation to obtain the impact of the changes of system parameters on the system stability. On this basis, the sensitive parameters of the system are optimized through sensitivity analysis, Finally, the theory is verified by time-domain simulation to verify the correctness of the model.