Dense-wavelength-division-multiplexing (DWDM) filter is a very sensitive component in wavelength shift. The temperature shift of central wavelength (TSCW) of filter is depended on the mechanical properties of the stress. In this paper, a modified Stoney's equation was applied to analyze the thermal stress of DWDM filters for the reason of the thickness ratio (thin film thickness/substrate thickness) larger than 1%. The phase-shift interferometer and TSCW were applied to measure and achieve the coefficient of thermal expansion (CTE), biaxial modulus, temperature optical coefficient, stress optical coefficient, and Poisson ratio of DWDM filter. Based on this method, we can obtain the CTE of DWDM filter 0.87pm/°C,the biaxial modulus 41 GPa, Poisson ratio 0.22, temperature optical coefficient 1.4×10 -5/°C, and stress optical coefficients -1.9×10 -12/Pa. To achieve zero TSCW for a DWDM filter, the CTE of the substrate should be 10.36ppm/°C.