Abstract: The proposal of digital concepts such as smart mines has more and more demand for three-dimensional spatial data, and at the same time, the stratigraphic model is not limited to intuitive display, but more demand lies in the analysis and processing of geological structures such as stratigraphic properties and faults.In view of the lack of internal attributes during the reconstruction of the geological model, the three-dimensional reconstruction of the geological structure under the volume data structure was discussed with a mining area as the research object. Firstly, an appropriate three-dimensional geological surface model is constructed according to the borehole data, and the three-dimensional reconstruction of the surface model is carried out by the local method for the fault part. Then compile the Tetgen algorithm to get the Tetgen.a static library file, on this basis, the surface model is tested for initial models such as closedness and intersection. Call the library file to read the vertices and patch data of the face model, and use the split function to divide the structure twice to complete the reconstruction of the tetrahedron model. Under the premise of considering the quality of the tetrahedron, adjust the split parameters to obtain a suitable boundary aspect ratio, thereby obtaining the optimal tetrahedral grid. Thus, the three-dimensional reconstruction of the geological body and the fault structure voxel model is completed. The feasibility of this method in geological modeling was verified with the help of a coal mine data. With the help of the collected roadway point cloud data and the collected borehole data, the three-dimensional reconstruction of the geological layer and the expression of the fault structure were completed by the method of tetrahedral reconstruction. The results show that the 3D model reconstructed by the volume element structure can express the internal properties, and at the same time, it also has good applicability for special geological structures such as faults, and the reconstruction of the geological body completed by this method is convenient for the subsequent application of the spatial analysis of the geological body to provide favorable data support for the construction of digital mines.