Ecological environment and land鄄use changes brought about by human activity are one of the highlights of the global change research. In complex natural ecosystems, among the various components of material cycles, energy flow and information delivery is usually expressed as a flowing form. Its path, direction, intensity, speed have an important impact on the ecosystem. This article analyzes the origin and development of ecological flow. The energy flow, material flow and information flow from the three areas to understand the ecological flow structure. And it gives a summary and review of relevant theory and analysis methods. On the basis of the existing studies, it analyzes the ecological flow in a typical half鄄 sown semi鄄natural farmland ecological system. For example, through ecological indicators, such as network connections and the pure comparative analysis of natural ecosystems and ecological stream flows, paths and intensities of human activity enhances the flexibility of ecological systems, but disrupting the stability of the original. Conventionally, a single conservative medium is allowed as to the quantification of ecological flows, for example materials (e.g., grams of carbon) or energy (e.g., kilojoules) , which is the major constraint during network construction. However, more than one kind of flow operates in ecosystem. Ecologists have been focused on applicable methods for a unification of all the eco鄄flows. Of which, emergy analysis and extended exergy analysis were invented respectively. Emergy analysis was to integrate the value of free environment investment, goods, services and information in a common unit of measurement via solar transformity, which makes it possible to evaluate all of the eco鄄flows (materials, energy, and information) with ecosystem. On the other hand, extended exergy analysis also provides a unified way to measure various flows with solid scientific basis, and provides a wide and clear vision of the use and degradation of resources and energy. Research foundation of ecological flow quantification have attained, but there are still many problems in future studies, which still need to be systematically explored.
