An overexcitation limiting method and system for an excitation regulator, the overexcitation limiting method for the excitation regulator comprising: determining an inertia time constant; collecting an excitation current of a generator, and calculating a first calculation result according to the inertia time constant and the excitation current; comparing the magnitude of the first calculation result with the magnitude of a first comparison value to obtain a first comparison result, and determining an output result according to the first comparison result; when the output result is a second numerical value, starting an overexcitation limiting inverse time limit adjustment so as to reduce the excitation current to a first preset value.