Laser three-dimensional (3D) display system based on polarization compensated liquid crystal on silicon (LCOS) optical engine compensates the polarization loss of the traditional LCOS optical engine, light of different polarizations entering into the optical engine is utilized in the process of the imaging process, each polarization is directed to one of two LCOS panels. In two-dimensional (2D) operation, the same image is presented on each LCOS, producing a double-brightness image. In 3D mode, one LCOS produces a right-eye image and the other produces a left-eye image. The images are optically combined and leave the projector through the same projection lens. This improved optical engine realizes 3D display，as well as enhances the efficiency of the optical engine when working in 2D display mode. This approach is highly efficient in that nearly 100% of the light emitted by the lasers utilized.