Due to the technical factors such as analytical design and virtual prototyping, the simple but representative sliding bar was chosen in this paper and its mathematical model of working contour was established by using the analytic method. And then, the parameterized model and VRML file structural drawing of sliding bar were given by using double extrusion method. It was proved that the components of the tripod universal joint were formed easily by using the double extrusion method based on Extrusion nodes. In addition, the tripod universal joint assembly model was also accomplished by using Inline nodes and bottom-up assembling method.