Abstract: Accurate calculation of the spotlight center position on the image is important to improve target localization accuracy for compound eye system. A method of calculating the spotlight position was introduced based on the symmetric property of the energy field. The position of main light on the image was defined as the position of the light spot on the image, and can be get by calculating the point of the spot energy centre on the image. Simulation and real images were used both with gray gravity method and energy method respectively, and the results show that energy method agrees with ideal position. Incident angle was calculated from the position of the image spot, the result shows energy method is also better than gray gravity method.