A novel interleaved demultiplexer based on polarization beam interferometer is proposed. The configuration and basically principle were analyzed by means of birefringence crystal and polarization beam interferometer. With simple experiment, interleaver does separate DWDM odd and even channel into two groups with the power equalization and satisfied with ITU T suggestions. The two channels isolations are 10.6 dB and 14.64 dB respectively, -1 dB bandwidth are 0.7 nm and 0.4 nm, respectively.