Abstract: Based on threephase gridconnected matrix transformation model of Tfilter, Tfilter based uncertain interconnected largescale system model which is threephase gridconnected nonlinear coupled is built according to circuit analysis laws. Through matrix transformation, the nonlinear coupled model can be transformed into linear coupled system, then threephase gridconnected nonlinear coupled largescale interconnected system model based on Tfilter that can be analyzed by using of decentralized robust control strategy. Based on stability analysis, the design method of decentralized robust controller of uncertain largescale interconnected system is given. In addition, the design method of control law is applied to Tfilter case of a 500kW gridconnected wind generator, and the simulation results show the feasibility and validity of this method.