In order to suppress the forced oscillation of the power system,the damping coefficient of the system is improved by setting the parameters of the UPFC main controller.Then,the auxiliary controller is added into the main controller to track the forced oscillation power fluctuation and to output the inverted power wave to suppress the system forced oscillation.It can further improve the system damping coefficient and enhance the suppression ability of the UPFC to the forced oscillation in the system.A model is built in the PSASP simulation platform to verify that the proposed UPFC main controller and the auxiliary controller can effectively suppress the forced oscillation on the tie line between the system regions.Thereby the damage to the system caused by forced oscillation can be minimized.