The invention relates to a UPFC-based forced power oscillation suppression method. The method comprises: a series side and a parallel side are controlled respectively; an oscillation signal of a UPFCinstallation bus is collected; deviation signals are formed at the series side and the parallel side respectively; the deviation signals are filtered by a gating link and the filtered signals are outputted to a lead-lag link; parameter designing is carried out on the lead-lag link by using a method based on synchronous torque coefficient compensation; the two output signals are superposed at a parallel-side voltage and a series-side impedor of the UPFC respectively; and the parallel-side voltage and the series-side impedor are adjusted to change a resonant frequency in a system oscillation mode. According to the invention, with resonance frequency control, a defect that the traditional damping control can not effectively suppress the forced oscillation is overcome and resonance frequency adjustment can be carried out only at a resonance frequency point is realized, so that the effect of the resonance condition of the system is destroyed, the forced oscillation is suppressed effectively, and other oscillation modes are not affected.