Abstract: In this paper, a whole are a thickness method was proposed for constructing seamless 3D stratum models. Using bore hole data as the data source, roof and floor DEMs for all stratum were constructed according to the same grid span. Then, theDEMs were transformed into a TIN model with topological relationships. All pinch outlines were as sembled and appended to the relevant stratum. At last, in additiontoa z coordinate, all the TIN models for stratum will now have the same vertex number, same x, y coordinates, and same topological relationship. Experiments showed that: ① this method canconstruct as eamless stratum model, ② is apt to convey special geological phenomenon alike pinch out and lens body and soon, ③ the 3D stratum model is easy to section and analyze, ④ and makes it easy to construct topological relationships between stratum