Abstract: In view of the issues of the dependence on manual intervention and of the low efficiency in finite element mesh generation, an algorithm for rapid generation of finite element meshes from geometric models is proposed by the base of the octree method. Firstly, the computational domain is determined according to the geometric model and the boundary face information is extracted, and the initial size parameters are set to construct the initial mesh model. The size distribution of the mesh model is constrained by the geometric characteristics of the boundary face, and the octree is divided recursively and equally according to the 2∶1 division principle to complete the automatic mesh division of the balanced octree. Then, the relative tolerance parameter is set. When the intersection point between the balanced octree mesh and the geometric model is within the tolerance range, the intersection point is replaced by the mesh node, and the finite element mesh is initially generated after the cut topology calculation is completed. Finally, the Laplacian method is used to optimize the boundary mesh, and the finite element mesh model is highly consistent with the geometric model. This study takes the Building Information Modeling (BIM) of underground caverns as an example, and uses the algorithm and the manual finite element modeling method to mesh it, generating two finite element meshes. The simulation results of the mesh quality inspection show that the mesh quality generated by the algorithm meets the requirements of engineering practice. Numerical simulations of the entire excavation process were conducted on the two meshes, respectively. The results show that the magnitudes and distribution patterns of the displacements and stresses of the two are basically identical.