The axiomatic design theory is applied with the product design knowledge expression of abrasive machine tools, making it possible to convert the implicit knowledge created in the study process into the explicit knowledge that will be shared all over the organization. The design knowledge created in the design and developing processes is divided into functional requirements, design parameters, design constraints and design coupling. In this paper, not only has the function-structure knowledge information mapping been analyzed, but also the implementation steps of product knowledge expression have been provided. Moreover, the matter-element model of the product design heterogeneous knowledge of the abrasive machine tool is established and the heterogeneous knowledge semantic rule is described. Finally, through a case of product design knowledge expression which is applied to the MLL60 abrasive flow machining tool, the correctness and practicality of this method are verified.