Abstract: Combing 3D geological modeling and numerical simulation of geotechnique,and using the advantage in modeling geological characteristics,precise geological models were provided for numerical simulation software.An approach to 3D geological modeling,suitable for automatic hexahedron mesh generation,was formed based on the section model method.Accordingly,a technique for automatic hexahedron mesh of rock-mass with complex structure was realized using multiply mapping mesh.This technique was used successfully on the feasibility analysis of mining under the left bank of Xifei River in Yangcun Coal Mine.