Abstract: The fixed jacket is an important facility for offshore oil and gas exploitation. It is welded by intersecting steel pipes and perform a space truss structure. The main component of the jacket is T/K/Y joint, which consists of a large number of saddle shape structures. The processing and welding of saddle shape are commonly executed by two-dimensional sticker method at present. Furthermore, there is no software to directly realize the parametric three-dimensional modeling of saddle shape. A mathematical model of saddle shape is established on the bases of analyzing the mechanism of saddle shape in this article. In addition, a general saddle shape modeling software is developed under Unity3D environment. The software realizes the parametric three-dimensional modeling of saddle shape and provides an accurate model for intelligent welding.