The mass customization can make customized products with the mass products efficiency, which will become mainstream manufacturing mode in the 21 century. The design for mass customization is the most important factor in the mass customization, on the base of extracting the excellences of the modulization design and the variant design, the article brings forward an idea of module-based variant design. Combining with the technologies of module coding, database, case-based design and CAD, The idea has been used in the customized design of the equipment of pushing and measuring automobile chair track, some equipments have been designed and manufactured successfully.