Sustainable product design has become the tendency of the product design because the degradation of the environment. However, there are no effective methodologies or framework designers and developer eager to. This paper base on the soft system methodology present a methodology which is effective to the idea generation phases in sustainable product design process. From the need identification to the idea generation, sustainable product design criteria and relationship between it and customer requirements, 39 engineering parameters, 40 inventive principles were use in the methodology. An example is illustrated to show the process of this work flow, and the result show the effectiveness of the methodology.