In the optimization design and analysis of expandable casing joints, it is necessary to modify the joint parameters repeatedly and establish the 3D model of the joint efficiently and quickly. This paper presents two parametric modeling methods of expandable casing joints with Unigraphics (UG). After the joint model template is completed in UG, one of the two methods uses the development platform Visual Studio to write an executable program with modifiable structure parameters and thereby achieve the secondary development and modeling of the expandable casing joint. In the other method, a dialog box is designed on the basis of the PTS module and parametric modeling is performed through the reuse library. An example of 3D parametric modeling of expansion casing joints is also provided in this paper. The proposed parametric modeling method can effectively reduce the repeated modeling time in the numerical analysis of expandable casing joints and improve work efficiency.