Abstract: The main point of 3D geo-fencing is to determine the location relationship between the spatial target point and the enclosed fenced area, and the judgment of this relationship can be attributed to the point inclusion problem. The classical ray method solves this problem with singularity in the judgment of the boundary, but the judgment of the boundary is relatively common in practical applications. To solve this problem, this paper proposes a fencing algorithm that transforms the relationship between spatial target points and 3D geo-fences into the position relationship between points and surfaces or planes. When the type of fence was a three-dimensional surface, a concrete mathematical model was abstracted according to the shape of the fence, and then the relationship between points and the model was judged; when the type of fence was a three-dimensional plane, the concave polyhedron was dissected into multiple sub-convex polyhedron and formed into a BSP tree by combining the two-dimensional spatial partition tree with the idea of convex dissection, and then the relationship between points and sub-convex polyhedron in the BSP was transformed into the relationship between points and each plane by our proposed linear equation system algorithm. The experimental results show that the algorithm can accurately determine the relationship between points and 3D geo-fences, and effectively reduces the response time of the fence determination results.