The concept of spattio model is proposed firstly in this paper. Furthermore, it points out that the graphic system based on spattio model will degenerate into a simple geodatabase if it doesn't have the ability to dynamically generate spatial relations. At last, the paper proposes the new method called four-adjacent mathematical model (4-adj model) based on Voronoi diagram to dynamically infer the spatial relations in spattio model, and gives the only complete inference rules, together with the advantage and disadvantage.