Abstract: In product R&D, companies often need to select R&D technology route for product combinations with alternative relationships. Based on the goal of optimizing the cost of the product portfolio of the company, a theoretical model is constructed. Considering the two technical routes of common technology R & D and special technology R & D, and key factors such as market substitution rate, analyze and obtain the constraints and equilibrium results of product R & D investment in different situations. By comparison, the decision-making plan basis for companies to select technology routes is obtained, and the profit change trend of different product R & D technology routes under the effect of market substitution rate is predicted.