As a kind of important implementation means of sustainable tourism, ecotourism has caught much more attentions of researchers from tourism, ecology, and other related fields since it had been put forward. This article summarizes the progress in foreign and domestic research on ecotourism during the post twenty years.As far as foreign research, many instinctive research achievements are accomplished, more and more foreign scholars focus their research on ecotourism, and many international organizations take part in the practice of ecotourism. Among many types of ecotourism defined from different points of view, the main criteria are impact of tourists' activities and the quantity of tourists. These double aspects are interrelated, and the former is more highly stressed. Furthermore, there are many theoretical and case studies of ecotoursim planning and management. The techniques and modes of ecotourism planning and management are generally accorded with those of tourism. Especially, function zoning is the key. Then, the basic characteristics and development trends of ecotourism research in china are analyzed. Four essential aspects include ecotourism types and zoning studies, advantages and disadvantages analysis, ecotourism destinations studies, and ecotourism planning and management. Function zoning, management of tourism, and community participation are particularly important. Based on summing up the limitations compared with foreign studies, the authors finally put forward some important suggestions for further research on ecotourism.