The shortcomings of the traditional description of the engineering product are shown. It is proposed to represent the design of the product and its details with a structured set of corresponding modules, in the form of a graph of a hierarchical structure. The characteristics of the structure of the product graph are considered: the number of levels, nodes, branches. The description of the structures of products by a hierarchical graph at the first level makes it possible to identify functional technological modules of the products and, on their basis, to construct a unified classification of products as objects of exploitation. Representation of parts by a set of modules allows you to identify modules based, working and connecting surfaces and on their basis to build a single classification of parts, focused on different stages of the product life cycle. The presence of a unified methodological base allows you to manage the development of product designs, minimize duplication in the creation of new designs and effectively develop technologies for their manufacture.