Abstract: Spatial elements on the map are generally presented as groups. Compared to the single object, there are more difficulties to compute the direction relations between object groups due to their complexity and diversity. In this paper, the direction Voronoi diagram model is extended according to the characteristics of direction relations between object groups, and based on the model the direction relations between object groups can be computed correctly. Its main procedure is: first, construct the constrained Delaunay triangulation of all sub objects of the reference group and target group; and then form the visible scope; finally, calculate the direction Voronoi diagram so as to describe the direction relations. The experiments show that the model can describe accurately the direction relations between object groups in various complex cases.