Earth science have developed on the research thoughts, the spatial and temporal scale of research objects, research contents, organizing forms, and information communication, research methods since 1980s. The authors point out that Earth science have entered into the time of Earth system science and service for social-economic sustainable development. In the 21st century, the Earth science will focus on the interaction in the interior of Earth system, the driving process of the Earth evolution, geo-information/digital Earth, Earth managing science/environment protecting/resources services, and multidisciplinary studies.