The embodiments of the invention disclose a synchronous generator power angle real-time measurement method and device. According to the synchronous generator power angle real-time measurement method and device, the actual measured value of the power angle of a generator in each electric cyclic wave is obtained through a power angle direct measurement method; the synchronous reactance of the synchronous generator is obtained through inverse calculation; a plurality of groups of power angle values in each electric cyclic wave are calculated in real time according to the synchronous reactance which is obtained through inverse calculation, a plurality of groups of set-end voltage phase quantities, a plurality of groups of stator current phase quantities, and the phase angle differences of the set-end voltage phase quantities and the stator current phase quantities, wherein the set-end voltage phase quantities and the stator current phase quantities are acquired at equal intervals from each electric cyclic wave; and the oscillogram of the power angle dynamic change of the generator can be obtained. With the synchronous generator power angle real-time measurement method and device of the invention adopted, the technical problems of low sampling rate, low real-time performance and incapability of reflecting the real change condition of a power angle in real time of a power angle direct measurement method in the prior art, and the technical problems of large deviation of a calculated value and a real value, and low accuracy of a calculation method according to which a constant impedance parameter is adopted to calculate the power angle of the generator can be solved.