Abstract: Based on the spatial position and the geometric characteristics of geographical objects,we present a method to uniquely identify geographical objects by combining their rank Quadtree grid index with spatial morphology.Based on the classic rank Quadtree grid method,we devise an algorithm to extract representative points,outline,and orientation of geographical objects in each grid.We integrate the geometry and grid information to achieve the unique identification of spatial objects.The method is applied to Nanjing city in China to identify the unique spatial location of spatial objects,and it shows improvement in the speed of spatial positioning,searching and querying of spatial objects.