Abstract: A new optical multilayer design for 45 incidence angle on PBS mirror is introduced. Compared with the traditional method of three stocks periodic multilayer design on PBS mirror, the new method is different in basic principles, which is called as non-periodic gradient multilayer method. It is based on the concept of changing the layers from period to non-period orderly. The purpose is to influence Brewster angle sensitivity effect on PBS mirror. Only two kinds of coating metrical were used on the substrate of SF75 prism glass deposition multilayer. P-polarization transition was over 70% and S-polarization reflection was less than 0.4% when incidence angle changed from 39 gradually to 51. The bandwidth of the polarization cutoff was expanded to 400 nm~700 nm. The new design for LCOS display system improves optical performance, simplifies process and reduces coating time and production cost.