The work aims to design a multilayer film structure which exhibits high average reflectivity in 380～455 nm waveband, and low average reflectivity in 500～760 nm waveband. Genetic algorithm and truncation selection strategy were adopted to design the multilayer films structure by introducing ecological niche technology. Tolerance evaluation function of good flexibility was chosen to endow functional film with anti-reflection and enhancement reflection characteristics in visible light band by changing target reflectivity. Overall film structure parameters required to meet spectral characteristic requirements were obtained by using eight-layer structure of alternate refractive index materials. When the materials were zinc sulfide and magnesium fluoride, and were 324, 142, 68, 46, 51, 51, 56 and 145 nm thick, respectively, average reflectivity of the film was up to 88.54% in 380～455 nm waveband, and only 2.75% in 500～760 nm waveband. According to different collocation of several common optical film materials, refractive index difference of refractive index materials shared the same trend with average refractive index difference between two wavelengths band. The difference of average reflectivity between two wavebands was 86.54%. When the refractive index difference between two materials was 0.92, average refractive index difference in two wavebands was 86.54%. The algorithm can effectively optimize the multilayer film structure. Two materials differing a lot in refractive index shall be selected as far as possible to obtain ideal blue light filter functional film.