The biased LED illuminated light pipe angle segmentation and its virtual image array forming principle were reserached. The light pipe size was calculated according to the biased LED position and divergence angles, and then optimizated with front imaging lens, intermediate image polarization conversion system, backend integral lens and polarization beam splitter. The polarization conversion system structure was determined by the optimized intermediate image distribution to insure the polarization conversion of luminous energy within the range of LED divergence angle and realize the uniform illumination to color-filter liquid crystal on siliconsize. A color-filter liquid crystal on silicon projection optical engine was finally designed with the white LED, wich can output light flux of 12.8 lumens per watt(the LED efficiency is about 114 lm/W) with 93% irradiance uniformity. Comparing with the optical engine without polarization conversion, the proposed optical engine enhances the light efficiency of the color-filter liquid crystal on silicon micro-projection system and enriches the light pipe applications while maintaining the homogeneity.