Based on the optical film theory, the membrane system was introduced to optimize the evaluation function, and the TFC software was used to optimize the membrane system, so that a 0°to 75°wide spectrum of P-polarized light beam splitter was designed. In order to produce the beam splitter, H4 and MgF2 were chosen as high/low refractive index materials, and the electron beam and ion assisted deposition techniques were adopted. During the experiment, the film thickness error was analyzed and a crystal was used to control the highly sensitive layers, which solved the accuracy problem in the film preparation process. Utilizing the inverse analysis method to simulate the experimental results, the P-polarized light transmission spectrum curves become smoother by changing the thickness of the correction factor. The spectral testing shows that the average transmittance of the prepared beam filter is 60.3% with vertical incidence P-polarized light, which meets the requirements of the system.