Abstract: Based on the characteristics of product innovation design, product innovation was designed into several stages: requirements analysis, problem-finding, problem-analyzing, problem-solving, innovative solution-generation and solution-evaluating. To help designers find problems, analyze the problems and solve the problems, the innovation model based on problem-solving was developed and the approaches to find problem were presented. In addition, different types of problems in product innovation design were analyzed; a systematic model supporting problem representation was put forward. Based on internal variable of the problem, the problems were divided into four grades and the strategies for solving each grade of problems were presented. Besides, several examples were cited to demonstrate the feasibility of the models and methods. Finally, a preliminary prototype software system of computer-aided design for product innovation was developed.