Modular design can shorten the product development cycle and enhance the product research and development capability of enterprises. To better solve the problem of module interface coupling after module partition, the present modular product design method has been improved based on the theory of inventive problem solving and axiomatic design theory. This article summarizes the engineering parameters commonly used in modular design based on the requirement analysis and conflict problems of modular structure design. And in the process of dividing the functional modules by fuzzy clustering algorithm, we propose defining and classifying the principle (technical) correlation between parts by these parameters. Then the coupling relation of each module interface is analyzed by the design matrix of axiomatic design and the conflict solving tool of the theory of inventive problem solving is utilized for decoupling. Finally, the high chair is taken as the design object and the design process is used to verify the feasibility of this method.