论述了虚拟地球的五个特征和建立数字地球模型的关键技术；在数字地球建设、研究和开发中，应密切从我国经济建设的需要出发，抓准、抓住制约我国经济建设的四个重大问题；并论述了数字高程模型应用的七大工程和研究领域。

The digital earth model is composed of three parts： digital frame model, digital elevation model, and digital earth-unit model. The question of building virtual earth in science mainly includes two sections： building the digital earth model and applying and developing modeling information effectively. The five characteristics of virtual earth and the key technologies for building digital earth model are introduced. This paper also discusses the seven engineering fields in which the digital terrain model is widely used. In the process of constructing ,researching, and developing the digital earth model, attention should be paid to environment pollution, plough land decrease, waterlogging and east-west regional variances, which have influence on China´s na-tional economic construction.