The invention provides a microwave frequency measuring method and device based on an optics frequency comb, and belongs to the microwave frequency measuring method and device technical field; the method comprises the following steps: dividing a laser signal formed by a laser and with the frequency fc into two parts, and using an unknown RF signal with the frequency fRF to carry out carrier suppression double-sideband modulation for one of the said two parts; beating frequencies of a carrier suppression double-sideband modulation signal and an off resonance light frequency comb on a narrowband photoelectric detector; parsing the frequency spectrum of the beat frequency signals, thus obtaining frequency information and power information of the two beat frequency signals; determining the frequency of the incident RF signal according to determined i, f1, f2 and a formula (7). The measuring device comprises the laser, a first coupler, an intensity modulator, a programmable filter, an erbium doped fiber amplifier, a double parallel modulator, a signal-generator, an electricity coupler, a phase shifter, a photoelectric detector, a frequency spectrograph, a second coupler, a third coupler and a fourth coupler.