A projection system for forming an image, comprising a light source generating light beam; a color wheel used for performing color separation on the light beam of the light source, comprising a motor having a shaft, a carrier pivoted to the shaft of the motor, and a plurality of color filters fixedly disposed at the periphery of the carrier to form at least one gap; and a digital micromirror element used for reflecting the performed filtered light beams of the light source from the color wheel to form the image.