Abstract: In order to increase the flexibility of optical signal demultiplex, a polarization-independent two-port multi-wavelength tunable filter was designed based on the electro-optic effect of birefringent lithium niobate (LiNbO3) crystal. On each arm of an asymmetric interferometer, mode-coupled electrode and phase -shifted electrode periodically alternated cascaded were set to realize mode conversion. Z - transform was utilized in analysis of Jones matrix to get the values of needed driving voltages to select wavelengths simultaneously. Narrow -band multi -wavelength with arbitrary distribution was simulated successfully in free spectrum range (FSR). 100% transmittance was obtained at each wavelength. The number of wavlengths had an influence on sidelobe of each wavelength. And sidelobe of 12 dB could be realized when three wavelengths were selected. Interleaver could also be obtained using this method, which had a flat passband and sidelobe of more than 20 dB.