Abstract: In order to improve the image registration speed and the matching stability，a sub-pixel image registration algorithm based on comparative distance is presented.And also，theoretical deduction and the result of experiments are given.And it has been proved that the algorithm has sub-pixel accuracy，and the precision is between 0.01 and 0.1.The results of matching experiment for 12 couples images have indicated the matching accuracy of presented algorithm has achieved 100%，and the time consumed is less than the RANSAC algorithm which is in common used in present.