In order to realize the adaptive exposure of the space camera, this paper proposes a method for adaptively configuring exposure parameters according to the highest luminance information of scene, which is realized by metering, calculating and imaging, successively. A large-scale array camera for light metering is installed besides the space camera. First, before the space camera is push-broom imaging a certain area, the image of this area can be obtained by metering camera with preset exposure parameters in advance, and the highest luminance information of this area can be measured. Then, exposure parameters of the space camera can be calculated by setting the highest luminance information measured before as the saturation luminance of the space camera. Finally, when the space camera focuses on this area after orbiting to a certain extent, the space camera could realize adaptive exposure by adopting exposure parameters calculated previously. Ground experiment results show that, compared with the method of using fixed small exposure parameters, the proposed method can reduce the number of under-exposed images. According to statistical results, the gray range of images is enlarged from 37 up to 253, and the image entropy also increases significantly. This method can adequately make use of the dynamic range of imaging system according to the current scene, improving the gray range and quality of the image.