In order to improve the service and observing efficiencies of space target surveillance equipment, a photoelectric measuring system was designed to determine the positions and distributions of clouds and to decrease the false alarm rate and damage possibility due to severe weather. This system employed a large field optical design and took a set of flat ellipsoid catadioptric lens as its core.By using an uncooled infrared focal plane array detector, it could collect sky images in all day long.A computer with a color card was used to perform pseudo-color and bracket removal operations and to get a pseudo-color image which could distinguish clean, haze, cloud and their transitions.Furthermore, the position information of the interesting points could be obtained based on the pre-established function between position information in the sky and pixels in the image. Experimental results demonstrate that this measurement system can collect cloud images in the sky above elevation 20°,and can offer a processed image every 5 s. The positioning accuracy of the system is 1°,which can achieve the position determination with large field for the cloud distributions and can improve service efficiency.