This paper mainly criticizes the viewpoints that put man against nature and society, and emphasizes that a harmonious relationship should be established among man, nature and society. Human, nature and society supplement one another and depend on one another for existence. Nature is the precondition and foundation for the existence and development of human and society. Social development is the condition and guarantee for the harmonious development of human and nature. Human development is the key point and the final destination of harmonious development of nature and society. The three factors should be looked on as a system so as to exactly orientate the function and status of human, nature and society, reasonably resolve the problem of sustainable development of the whole society and lead the human society to healthy development.