Digital earth, emerged at the end of last century, is a new strategic orientation for quantitatively studying the earth and a cross-cutting multi-disciplinary field of space science and technology, information science and technology, earth science etc. This paper describes the origin of digital earth and its development background of past ten years, conceptual model and framework, scientific and commercial sharing system, multi-level and multi-disciplinary application fields, as well as academic platform building capacity including international symposia and summits on digital earth, the International Society for Digital Earth, and International Journal of Digital Earth. Furthermore, the paper points out the important role of digital earth and its′ huge developing potentiality, and envision of constructing a digital earth science platform.