Abstract：The true three-dimensional strata modeling is a common issue for geology，three-dimensional GIS，scientific visualization and engineering application. After introducing and summarizing the theory and method of three-dimensional geology modeling，a true three-dimensional tetrahedron network(TEN) model of strata is proposed. The model represents three-dimensional stratum with a series of tetrahedrons，which can provide the best flexibility to fill regions defined by simplified boundary elements(i.e.，edges in two-dimensional，triangle in three-dimensional). Geological exploration hole is the main information for engineers to know the soil strata. Geological exploration hole are abstracted as scattered point data. Each point is the demarcation point between two different strata and a topologic dimidiate datum structure is designed. Based on these scattered points abstracted from geological exploration hole information，the three-dimensional TEN stratum model is reconstructed by Delaunay triangulation algorithm. The modeling method can disposal broken mutation such as failure and dwindle. At last，some assumed classic strata and strata of a practice project are constructed by the method. The model has the advantage of convenient for storing and fast visualization. The characteristic of construction method is taking advantage of computer more effectively. Because the model strata are represented by tetrahedron，the strata model can also be used as the FEM mesh and convenient for special analysis，such as settlement or seepage of soil.
