The invention discloses a laser frequency noise measurement method and a laser frequency noise measurement system, and belongs to the field of optical measurement. According to the method, a to-be-measured laser is adopted as a light source of an optoelectronic hybrid oscillator constructed based on an optical comb modulator. After that, the phase noise of a radio frequency oscillation signal in the optoelectronic hybrid oscillator is measured. According to the measured phase noise, the frequency noise of the to-be-measured laser is obtained. The optoelectronic hybrid oscillator is of a double-ring structure. According to the technical scheme of the invention, the frequency noise of the laser is indirectly measured through measuring the phase noise of the radio frequency oscillation signal. Therefore, the frequency noise and the intensity noise of the laser can be distinguished from each other. Moreover, the measurement sensitivity is extremely high.