Two approaches of building DWDM component incorporated with optical interleaver and thin film filter modules are discussed. A novel structure is proposed to improve the insertion loss uniformity, channel isolation, and the total crosstalk of such DWDM component. Theoretic analysis and experiment were performed on both the novel and conventional structure, and the result indicated that the side lobe of the novel structure′s spectrum is depressed from -30 dB of the conventional structure′s to about -50 dB. DWDM experiment by using at a 16 channel 50 GHz indicates that an improvement of 0.869 dB on insertion loss, 2.005 dB on insertion loss uniformity, 1.004 dB on adjacent channel isolation, 42.903 dB on non-adjacent channel isolation and 1.68 dB on total crosstalk. The novel approach can be used not only in the ultra-DWDM based on interleaver and thin film filter module cascaded, but also in DWDM based on array waveguide grating (AWG) to mitigate the technical difficulty and improve the specifications.