Abstract: In view of the problem that existing 3D modeling method of rock strata surfaces does not systematically consider the construction of 3D modeling of complex rock strata surfaces with geological conditions such as fault and collapse column, horizontal projection unit features of rock strata surfaces under different geological conditions were given by defining the projection degree and projection unit, and a 3D modeling method of complex rock strata surfaces based on unit division was proposed. Firstly, the horizontal projection unit and the spatial interpolation unit of rock strata surface were divided, and constrained Delaunay triangulation was performed on real projection unit by using horizontal projection unit boundary, space interpolation unit boundary, control point and control line of rock strata surface as constraints. Then interpolation points of the rock strata surface corresponding to vertices of the triangulation in each spatial interpolation unit were respectively solved, and the 3D graphics of the rock strata surface were drawn by using 3D computer graphics technique. The example analysis results show that by dividing the horizontal projection unit and the space interpolation unit, the complex rock face can be decomposed into several general rock facets so as to reduce the difficulty of 3D modeling; reasonable constrained Delaunay triangulation and spatial interpolation can effectively construct 3D model of complex rock strata surfaces.