A method for processing optical signals includes performing frequency mixing, photoelectric detection, analog/digital conversion, and dispersion compensation on received input optical signals. First-path polarization multiplexing optical signals and second-path polarization multiplexing optical signals. An initialization update process is performed on filter coefficients. Polarization compensation is performed on the first-path polarization multiplexing optical signals and the second-path polarization multiplexing optical signals by using the filter coefficients on which the initialization update is performed to obtain initialized x-path optical signals and initialized y-path optical signals. Preset x-path training sequences and y-path training sequences are synchronized by using the initialized x-path optical signals and the initialized y-path optical signals. If a synchronization result indicates that polarization cross occurs, the polarization cross is rectified.