Ecotourism is a new field in which the ecotourism develops and extends in depth. It is also the new tourist system produced by the diversified and advanced tourist activities. The author regards the ecotourism possesses six characteristics: (1) The traveling activities take nature as their stage; (2) Contents of tourism germinates the elegant quality of science and culture; (3)The traveling activities use ecological ideology as thinking base; (4) The carrying body of travelling activities possess the natures of diversity; (5)The tourists highly participate the activities; (6)Ecotourism is the high quality travelling to enhance the human environmental consciousness. Thus, ecotourism is the tourism of sustainable development which is to last for generations. It must not only meet the demand of tourism for contemporary people, but also retain the enough travelling space, good environment and sceneries for next generation in order to be used forever. So, drawing lines for ecotourism is the base for sustainable tourism. The author puts forward two types of new concepts of Antogenic Geo ecotoursystem and Allogenic Geo ecotoursystem for the productive mechanism of ecotourist sceneries. The paper discusses the potentiality of ecotourist resources. It expounds the inherent relationship between China Agenda of 21th Century and ecotourism, and suggests to put into effect the general plan of Chinese ecotourism development.