Abstract: The paper introduces three kinds of GPS timing and time transfer method.In this paper the principle of GPS timing for power system applications is also introduced,which includes synchronous voltage phase-angle measurement,power line fault location,synchronous sampling,online network consume account and energy management system(EMS).Especially,Two kinds of method are addressed detailedly.The paper gives the sketch of fault location of the two kinds method,and some test results are shown.Simultaneously,to confirm which power line causes the fault,various power lines have been taken into consideration.