Abstract: Engels once spent large amount of time in concentrating on natural science studies,and formed the book entitled "The Dialectics of Nature",which was compiled by the descendants.The book shows Engels's the dialectical view about nature different from Marx's view about the relation of between human being and the nature.Engels'view about nature has certainly contained the thought about the dialectical and unified sustainable development.And the Scientific Outlook is the extension of Engels'view about the sustainable development,and it is of profound theoretical significance and value in the modern times.