The invention discloses an ultra-high-resolution spectral measurement method and system based on all-optical Fourier transform and dual-optical-frequency-comb time domain interference. The method comprises: two optical frequency comb light sources generate two paths of ultra-short pulse sequences with a slight repetition frequency difference; one path of ultra-short pulse is processed by a chromatic dispersion effect to obtain a sweep-frequency pump pulse sequence and a time domain lens is formed based on a four-wave mixing principle; with the Fourier transform function of the time domain lens, conversion from the wavelength to time is carried out on a to-be-measured optical signal; after wavelength unification, interference superposition is carried out on the optical signal carrying to-be-measured spectral information and the other path of ultra-short pulse; and the obtained interference signal is converted into an electric signal and then follow-up processing is carried out to obtain the spectrum of the to-be-measured optical signal. Therefore, the ultra-high spectrum resolution is realized. The method and system are suitable for measuring an optical signal in any form; and the system cost can be lowered effectively.