The invention provides a method and a device for setting a low-excitation limitation parameter. The method comprises steps: a first characteristic curve for an equivalent transfer function of a generator system along with frequency changes in a set frequency range is acquired through a frequency scanning mode; under a low-excitation limitation parameter of the generator system, a second characteristic curve for a set transfer function of the generator system along with frequency changes in the set frequency range is acquired; the first characteristic curve and the second characteristic curve are used for calculating and acquiring a Nyquist curve for the generator system; and by using the Nyquist curve, the low-excitation limitation parameter is set according to a Nyquist stability criterion. The method and the device can be well applied to field low-excitation limitation parameter setting through the frequency scanning mode, and the stability of the generator system is not broken.