The polarization selective beamsplitter system used for a liquid crystal light valve (LCLV) full color image large screen display is a key subject. The function of such system involves both polarizing radiation and separating light ham into three primary colours. The properties of this system have great influence on the brihtness, contrast and colour distortion of the displsy system. The polarization selective beamsplitter system consists of four polarizers or non-polariser and three trimming filters. Whole system is immersed in an oil tank. Such a system has good performance, especially high extinction coefficient.