A three-dimensional (3D) optical model is developed for small color pixels in vertical alignment nematic (VAN) mode color filter liquid-crystal-on-silicon (CF-LCoS) microdisplays. First of all, the electromechanical characteristics of color liquid crystal (LC) cells are analyzed to achieve the orientation structure of the LC director. Then, the optical reflectance of the cell is calculated by using the extended Jones matrix. Finally, the optical reflectance on the pixel array is reduced into the displayed color image by adopting a standard RGB representation. In order to verify the accuracy of this 3D optical model, the simulation result and the observed result are compared. The simulated optical reflectance is in good agreement with the experimental result.