A new dual-wavelength compensation method for the variation of bias phase in Mach-Zehnder(M-Z) interferometer was proposed and experimentally demonstrated.A none-fading compensated signal could always get when a space of two wavelengthes was specially selected by adjusting the one center wavelength of the two sources.As a experimental result,this dual-wavelength copensation method can work arbitrary bias phase as against the single-wavelength method.Thus it can effectively solve the signal fading problem of the interferometer,which may arise from the variations of enviromental parameters such as the fluctuation of ambient temperature et al.