The present invention relates to communication technologies and provides a method and a device for FSK/GFSK demodulation, the method comprises: determining a digital information vector group {Vl(i)} of a codeword a[k] to be demodulated and a corresponding phase matching vector group {θi(i)} within the duration of (2M+1)T; determining a received phase vector {tilde over (φ)}(i) of a received FSK/GFSK baseband signal φ(t,a); determining an average phase difference βl between {tilde over (φ)}(i) and θl(i); calculating the phase matching degree Ql between {tilde over (φ)}(i) and θl(i) after removing the impact of the average phase difference βl, and determining an l value corresponding to the phase matching degree Ql being the maximum; and determining the a[k], corresponding to the l value, in the digital information vector Vi(i) as a demodulation result. Because the impact of the average phase difference is removed during phase matching, the accuracy of phase matching is increased, and the performance of the phase domain demodulation technology is improved.