This report describes research done on actual automobile headlights with an aim to developing a means of using personal computers to simulate the flow of light from auto headlights. We were also able to establish optimal geometric shapes for reflectors and coverglasses. Afterwards, computer-aided ray tracing and ray attenuation operations were performed to calculate illuminance distribution results. Moreover, comparisons were made to determine the computer simulation analysis results and the matching of different parts, as well as the relative distribution of light rays. In this way, the accuracy and reliability of the computer simulation analysis could be verified.