A method for optimizing the space camera system and its parameters is proposed in order to improve the quality of remote sensing images. First, a clamp voltage value is set in the space camera and a largescale array camera for light metering is installed besides the space camera. The image of a certain area can be obtained by metering camera with low and high exposure parameters before the space camera scans this area by the pushbroom mode, and the lowest and the highest luminance information of this area can be measured. Then, exposure parameters of the space camera can be calculated by setting the difference between the highest and the lowest luminance measured as the saturation luminance of the space camera. The value of clamp voltage is set according to the lowest measured luminance. Finally, when the space camera focuses on this area after orbiting to an appropriate position, the space camera images the area with the exposure parameters and the clamp voltage above, and thus the adaptive adjustment of the space camera parameters is realized. Ground experiment results show that the influence of atmosphere on the gray level is removed before imaging and the radiation resolution of the image is improved by optimizing the space camera system. According to the statistical results, the gray range of images increases by 80.7%, and the image entropy also increases significantly. This method makes use of the dynamic range of the imaging system sufficiently based on the current scene, and improves gray level and image quality of the image.