The invention discloses a multi-light-source frequency-stabilization system and method in a multi-subcarrier system, and relates to the field of photo-communication. The multi-light-source frequency-stabilization system comprises n independent laser devices, an N*2 combiner, two arrayed waveguide gratings, n sets of detection devices and n feedback circuits, wherein the N>=n>=1, the n independent laser devices are used as a multi-wavelength light source, the N*2 combiner converges n paths of light with the different wavelengths, and evenly outputs the light to the two arrayed waveguide gratings, the arrayed waveguide gratings conduct smoothing and output two paths of monitoring light corresponding to different light sources, each detection device comprises two photodiodes which respectively receive the two paths of monitoring light corresponding to the same light source, and the feedback circuits are respectively connected with the detection devices and the laser devices corresponding to the feedback circuits, conduct comparison on two luminous powers detected by each detection device and conduct fine adjustment on the output wavelength of the laser devices corresponding to the feedback circuits according to the result. The multi-light-source frequency-stabilization system can be used in a DWDM and Nyquist-WDM system, the cost is low, and the wavelength intervals of the independent light sources are kept stable.