Due to the changeable brightness outside the tunnel, the lighting brightness at the exit and entrance of the tunnel needs to be adjusted in time, so as to ensure that the driver can feel the difference of light intensity within the range that the human eye can adapt to when passing through the tunnel. In this paper, a tunnel lighting control strategy based on variable reduction factor is proposed, which can ensure that the lighting around the tunnel is within the range that the human eye can adapt to at any time. Through the field data collection and comparison and experiments, it can be shown that the lighting control method not only can improve the lighting quality in the tunnel, but also have better energy- saving effect and can reduce the cost of manual operation and maintenance.