Abstract: The ore-body block model is not only widely used in ore grade and reserve calculation，but used in the optimization of the final mining boundary and mining plan in the open pit.According to the investigation on octree storage structure and OBB intersection test theory based on the separating axis, it is proposed that the three dimensional space of ore body is firstly subdivided into small blocks by the octree, and the ore-body is approximated by a series of small unit blocks; Then, the spatial relationship between unit blocks and the ore boundary is detected by the OBB theory to subdivide the unit blocks of intersection.According to judgment of the point in the polyhedron or not to ensure block model constrained in the surface model, ore-body boundary can be fully approximated.Finally the ore body block model of Sandaozhuang open pit is created by this method, showing it an effective method which can meet needs of production design for the mine.

Key words: Octree, Block model, Intersection test