Based on the situation of the space-based small moving target detection on space surveillance system,we introduce the way working on staring model,and then discuss the way of small moving target detection based on image registration technology. Through finding out the local min distance between stars as star map characteristic quantity,a novel star map characteristic quantity is proposed. This characteristic quantity is used to align the neighbor star maps in the sequential images. Through subtraction,the background consisting of evolving clutter can be removed and the small moving target in space is detected. The result of the test shows that the local min distances in star maps distribute well proportionally and the star maps match well.