Abstract: With the rapid development of the drilling industry, various drilling equipments are widely used in many projects. Advanced design methods of drilling equipments take an important role during the development of drilling equipments. This article proposes the method of automatic design based on the pro-development of SolidWorks for drilling rig's parts and explains the detailed courses with an example of the variable design for the chuck of the core drilling machine. After input necessary given parameters in the user's interface of computing basic parameters for the chuck compiled in the environment of Visual Basic, the relevant parameters of the chuck will be figured out automatically. In the user's interface of variable design for the chuck based on the pro-development of SolidWorks, inputting the diameter of drilling stem will lead to generate all parts' drawings and assembly drawing for the chuck in the environment of SolidWorks. The method improves design efficiency and economizes labor costs, also lays a foundation for the automatic design of an overall drilling equipment.