Abstract: This article Combined with the MicroStation software development platform of Bentley companies in the United States , using the MDL secondary development method, combined with the complexity of geological conditions of special coal mine, through the establishment of topography and graphics library, drilling database, database structure, etc. forming the ground terrain mesh surface, the three-dimensional borehole columnar body, structure grid, using data and graphics functions,which mainly from the study of coal mine process and key points of 3 d geological modeling, discusses the suitable a set of the concept for 3 d geological modeling , shows the effect of 3 d geological modeling and visualization. Modeling of 3 d mine and play an important role in the development of digital mine.