Abstract:Forest evapotranspiration is an important process in the water cycle of forest ecosystem, which has important effects on rational utilization of forest water resources , global water cycle and regional climate change . At present There are more about forest evapotranspiration research, this article through to consult the related literature at home and a- broad, mainly from the process of forest evapotranspiration, influence factor , measurement method and the advantages and disadvantages of each method and so on several aspects has carried on the induction and summary, can help to further understand the law of forest hydrology and forest ecosystem structure and hydrology.