In view of the evapotranspiration model which is based on traditional single-point calculations and can't consider the effect of watershed surface conditions on evapotranspiration,the paper used satellite remote sensing data and took Nanguang River basin in Sichuan basin as the research object so as to build distributed dual-source evapotranspiration model based on a grid unit. The model realized the calculation of whole process of evapotranspiration time and space in research area.The results show that the calculated value and measured value of evapotranspiration based on the site area of remote sensing data source have better consistency and relevance,the correlation coefficient is 0.744.Under similar weather and surface conditions, the sequence of evapotranspiration capacity: forest land >shrubbery> paddy field>dry land > grassland.The result can provide certain reference value for the space calculation of evapotranspiration in the watershed as well as quantitative analysis of effect of land use change on watershed evapotranspiration.