As a high-efficiency technology innovation, radical innovation (RI) can be applied for modern enterprises to achieve leaping-over development. It's the great significance for enterprises to upgrade technology and enhance the capability of the independent innovation. Based on TRIZ ideal final result (IFR) and technology evolution theory, the technology forecasting process of product technology system radical innovation is put forward. The paper offers a kind of innovation method for product radical innovation design on the stage of fuzzy front end (FFE), which considers the result as the final high quality ideas of FFE. As a case study, the direct shift gearbox (DSG) is investigated. The study shows that the adoption of this method makes the application of the initial stage of product development feasible.