When the space-based platform shoots the star-image pictures,the background and the camera have relative motion simultaneously.Thus the small moving targets can not be detected through the simple frame difference.Based on analysis to star image model,an image registration method is proposed by extracting feature points to match the same triangle.In the method,optimum threshold is selected for single frame image segmentation and background noise removal.Then,the bright stars are divided by the area,and the feature triangles are made up by the stars that meet the conditions.The motion parameters can thus be obtained in adjacent frames by matching the feature triangle.For reducing the complexity,the star centroid coordinate matrix is processed instead of the whole star image to image registration.Finally,the target track is obtained through a multi-frame track association.Simulation and tests demonstrate that the method can achieve high detection rates and low false alarm rate in the sequence frames.