With the development of science and technology, harmonious design will be one of the latest trends in modern mechanical products development. Based on the harmonious design method, the well synthesized quality products will be invented. It will have little negative influence on society and the natural environment, and the high utilization rate of resources and the most comprehensive benefits in the full lifecycle from planning, designing, manufacturing, packaging, and discarded. The harmonious state can be obtained between products with political, economic, cultural, legal, scientific, natural and social environments. The harmonious design is investigated from the harmony of design methods; the harmony of product function with performance; and the harmony of product with product, with human, with technology, with society environment and with natural environment. And the evaluation of harmonious degree and management system are studied in this work, too. Based on system engineering and economic, cultural, legal, scientific, natural and social environment factors, the formula of the complete system of products design is established. Therefore, the new vitality and higher market competitiveness of product can be achieved. Not only the design is for human but also for nature, for the harmony of human and nature.