Abstract: With the increasing scale of power grid and construction of AC and DC hybrid system, the application of UPFC has become one of the key issues. In this paper, the control characteristics of UPFC under different control strategies and its influence on power flow are studied according to different control needs. Firstly, modified models of conventional power flow equations are built according to different UPFC control strategies, in which conventional power flow calculation program is used to calculate power flow with UPFC directly. Then, through analyzing the power flow with UPFC, the steady-state control performance of UPFC and its influence on power flow are analyzed. In the end, the validity of proposed model and the method are verified by classical data, which will have a certain reference and guiding significance for the application of UPFC in actual network.