The 3D model of bad geology and special geoengineering geology of ZhengzhouWanzhou Highspeed Railway is insufficient, the geological phenomena are invisible, and the geological process is complex. Hence, the topographic measurement, geological data, mapping data and geological surveying data are analyzed and modified; 3D models of surface geological boundary, water system, traffic network, overburden, lens microgeological unit and karst system are established and analyzed by means of geological and mathematical interpolation combined with threedimensional surface model simulation; the interpolation and modification analysis of TIN, Grid, trend surface fitting and NURBS surface results are analyzed to obtain a method that describes the information of the object including geometric information, topological information, and attribute information. The method can describe the spatial information, i.e. geometric information and topological relationship, of complex geological bodies and the characteristic information of each geological unit, which can meet the needs of the expression and analysis of complex geological bodies and provide reference for threedimensional modeling in the representation and data of engineering geological boundaries.