It is an important research content for analysis of space security to detect the small targets with space-based observation platform. But it′s difficult to develop a fast, robust and automatically processing algorithm for some reasons: there are too many stars which have similar appearance with targets in space image and the observation platform moves irregularly. Based on analyzing star image model, a method of space target detection was proposed by triangle matching and maximum projection. First step is the sequence images registration with feature triangle and for reducing computation, the star centroid coordinate matrix was calculated. Then the maximum projection transformation for image sequences was used for detecting the moving small targets. Finally, simulation and test demonstrate the method can achieve real time and accurate targets detection with 200 sequence images.