In many application problems of CAD/CAM, people not only need to describe the exterior of solids, but also want to know the information within the solids. In the light of this situation, this paper displays the method of NURBS tri parametric solid modeling and some construction techniques. Also the paper discusses some applicational problems in CAD/CAM of dies, such as 3 D finite element mesh generating and mass properties calculation, which are based on this method.