Abstract: Taking the geological exploration engineering as our research objects, we propose a QTPV (quasi tri-prism volume) model and make research about the model manipulation. In this paper, QTPV data structure is analyzed. 3D QTPV data model and data structures are designed. Model manipulation algorithms, such as modeling according borehole sample data, model cutting, model partition into tetrahedron, are proposed. The QTPV model features have been discussed by making a comparison among 3DFDS, TEN and QTPV. A system prototype is developed based on the proposed model and manipulations on QTPV by using VC ++ and OpenGL graphic library under Windows environment. A set of real borehole sample data, which come from Inner Mongolia China, is used to verify the model and algorithms implemented in the system prototype.