Voltage of DFIG-based wind farm may collapse under the situation of irregular changing of wind speed or short circuit fault occurs, thus the wind farm will be out of work and the grid will be under threaten if the situation is terrible. As the most useful component in FACTS devices, UPFC can maintain voltage of wind farm , decrease the reactive power exchange and maintain system stability．In this paper, mathematical models of UPFC, DFIG-based wind farm are constructed on PSCAD/EMTDC .The power and voltage of wind farm with/without UPFC verifies that UPFC can improve dynamic performance of DFIG-based wind farm and make wind farm operate continuously．