Abstract: The acquisition of the geological block structure model which is based on stratified geological structure is one of the most important steps in geological modeling. In present construction methods, attention is merely paid to the extraction of geological blocks and the improvement of the algorithmic efficiency, but not the establishment of the topological relationship between geological blocks and their faces or the establishment of the topological relationship between geological blocks. In this paper, a new construction method is proposed, and its basic idea is: firstly, direction-edge and direction-triangle are extracted by making use of the relationship between the boundary lines and the faces; and then the sort-table of three-dimensional faces is established according to right-hand rule; finally, the positive and negative body of each face is obtained according to certain ergodic rules. This method can not only be used to automatically define the relationship between the geological blocks and their faces, but also indirectly analyze the adjacent relationship between geological blocks, so as to lay the foundation for the establishment of the three-dimensional geological structure model as well as the query and analysis of the three-dimensional topological block.