The invention provides an unified power flow controller fault state crossing method. The method comprises the following steps of step1, accessing an unified power flow controller into a power transmission line; step2, determining whether the power transmission line has a fault; step3, if the power transmission line has the fault, automatic adjusting a work state by the unified power flow controller so as to guarantee safe operation of the unified power flow controller. Compared to the prior art, by using the unified power flow controller fault state crossing method provided in the invention, an influence on the unified power flow controller when an alternating current power system generates a fault can be reduced, a rapid dynamic adjusting effect of the unified power flow controller after the fault of the alternating current power system is removed can be performed maximumly, and simultaneously coordination cooperation of safe operation between the unified power flow controller and the alternating current power system is realized.