Highly integrated miniature cameras based on CMOS sensors have been used more and more widely in spacecraft. Space camera can accomplish the key operation record, remote sensing and near celestial observation of spacecraft, and has the characteristics of small volume, light weight and intelligent. In order to achieve a good imaging effect, automatic exposure technology which is suitable for the space environment is indispensable. In this paper, a fast adaptive exposure algorithm is proposed for the particularity of space environment and the irreversibility of spatial tasks. The algorithm is based on energy analysis, weighting statistics on the target according to the statistics of the image, and using the lookup table method to calculate the optimal exposure time. The double objective adjustment range is set, so that the automatic exposure algorithm converges better. The experimental results show that the algorithm can obtain the best exposure time quickly and stably. The speed of exposure is fast and the stability is high. It is very suitable for space scene detection. The correlation algorithm has been successfully applied to multiple on orbit models.