To improve the efficiency of variant design, it is not only needs dimension variant design but also needs dimensional tolerance design method. The method to extract tolerance information from parametric model of a part, the method to calculate tolerance value of a dimension according to its accuracy class, the method to place tolerance information to a dimension are researched. A dimensional tolerance variant design method of part based on the above three methods and parametric technology is put forward. The dimensional tolerance variant design method is integrated into dimension variant design method and an integrated variant design method is obtained. An integrated variant design module which can be integrated into SolidWorks is developed. As an example, the methods and the integrated variant design module is applied to an output shaft and the methods and the variant design module are verified.