The invention provides a method for measuring a synchronous phasor. The method comprises the steps that a voltage transformer and a current transformer acquire a voltage signal and a current signal respectively; a secondary voltage transducer and a current transducer convert the voltage signal and the current signal into measured signals respectively; an FPGA module controls an AD sampling module to conduct AD synchronous sampling according to a clock synchronous signal and a synchronous pulse per second; an embedded processor receives AD sampling data of an FPGA. Regarding the shortcoming of a measuring method of the synchronous phasor of a conventional power system, with the combination of the characteristic of inputting the signals under the dynamic condition of the power system, the method can effectively improve the measurement precision of the synchronous phasor under the dynamic condition.