A novel multi-function DWDM optical filter composite module is proposed and systematically studied, complete theoretical model and numerical simulation results are givea Performance demanded for them by DWDM optical network and fabrication techniques are discussed also. Much effort was devoted to the modeling, design and analysis of bi-directional finite impulse response (FIR) type de-interieaver based on cascaded asymmetric M-Z interferometer. Adoption of wideband 3×3 fiber coupler in the structure provides such advantage as in-line monitoring of the fabrication process conveniently, meanwhile, attached by other optical components like optical circulator, fiber grating dispersion compensator, F-P wavelength channel monitor and MZI-DWDM, its function is strengthened, which is important for intelligent DWDM ail-optical network especially.