Abstract: In order to meet the requirement that the portable multi-band camera can be used in large-scale illumination environment, the exposure time adjustment algorithm of the multi-region mean weighted combined with the image entropy was proposed to resolve the problem that the impact of image reference mean to the performance of algorithm based on the multi-region mean weighted exposure time adjustment was heavy. The multi-region mean weighted exposure time adjustment algorithm was adopted for fast adjustment when the gray value of the image is too high or too low, and the image information entropy exposure time adjustment algorithm was used to eliminate the overshoot oscillation. Based on the portable multiband camera exposure time adjustment experiment, the exposure time was 31 ms, the eliminating oscillation time is about 180 ms. The results show that the use of the exposure time adjustment algorithm of the multi-region mean weighted combined with the image entropy can rapidly and stably choose appropriate exposure time, and the camera can get good image.