Abstract: The author firstly introduces the background of proposing eart h system science in the contexts of global major problems facing the human bein gs,globalization of the earth system,earth system science and traditional ear th science,elucidates seven features and six trends about earth system science .Second,he introduces in detail the concepts and research methods of earth sy stem science.The main contents include the research thought ,basic concepts an d methodology of the earth system process and earth system science.Third,a th eoretical basis of earth system science is constructed.The main contents are t he continuous dy-namic system of the earth system,discrete dynamic system,r andomness of the earth system,self-organiza-tion of the earth system and si mple giant system and complex giant system of the earth system.Fourth,the m otive power effect of the interaction between the subsystems of the earth sys tem science and various layers of the earth is introduced.Finally,the author proposes that the digital expressions of the earth sys-tem-the digital ear th and earth system science-are the scientific basis of the sustainable develo pment strategy.