The mechanical product concept design method based on reverse engineering (RE) is a new approach in the concept design domain. The functional pattern is thought as an effective carrier and medium of mapping function to structure, which provides an efficient path for expressing the intrinsic evolution rule of the complex mechanical qualitative structure. And it is used as the information organization unit and the assembly product information model, which could give some help to express the design knowledge effectively. Therefore, we proposed a mechanical product concept design method based on RE. The examples indicated that this method is feasible and it provides a practical technical way for the knowledge reuse and continue innovation of the existence products.