Planar targets have been widely used in the field of machine vision, and reordering the feature points on a planar target is of great difficulties and importance. As the current methods for that are of poor robustness, and are easily interfered by foreign objects or the image background, a novel method, which is of high versatility and is not easily affected by the interferences, is proposed in the paper. Cross ratio invariance and homographic relationship between the target plane and the image plane are utilized in the method. Experimental results show that the method is viable and robust to realize precise reordering of the feature points on planar targets in complex site environment.