An optical design of digital light processing projector accommodating three pieces of micro digital mirror array display panels is presented. The system is configured by the combination of a color separation unit and a color re-combination prism, which combines light signals from individual display panels and then directs the synthesized full color images projected onto the screen. The color separation unit comprises two dichroic filters set at 40 degrees with respect to the optical axis of the system and two reflecting mirrors with relay lens for guiding light. The color re-combination unit is contructed in the form of a modified x-prism for better achievement of image contrast, color saturation, and light efficiency. The present system out-performs systems based on the configuration of Philips prism in less occurrence of degraded image quality associated with teh thermal influence of the optical engine, short optical path in prism and back focal length of the projection lens, and the physical size and weight of the unit. Comparisons in overall optical characteristics of the proposed system and those designed by means of various modules of single prism, which operates color separation and color combination processes along same optical path through the prism block will also be presented.