For separating two wavelengths of 810nm and 850nm polarized light into two optical beams, keeping their polarization directions and pursuing the maximal degree of polarization, a dichroic beam-splitter at incidence angle of 45?is designed and fabricated, and it makes 810nm beam passed and 850nm beam reflected. Selected an apposite initial film configuration to control the separation of s- and p-polarization components, and optimized the the film configuration by the Global Modified LM method in Film Wizard software, and the phase and energy parameters meet the design target. TiO2 and SiO2 have been chosen as high- and low-refractive index layer materials respectively. Ion beam-assisted deposition, optical extreme value method, and quartz crystal oscillator have been used to control the thickness of films . The extinction ratio of obtained sample reaches 7000:1 in 810nm beam and 20000:1 in 850nm beam. This work realized phase and energy control of optical thin films to meet the demands of polarization states coding communication experiment.