The Yangtze River Basin is an important water resource supply area in China. The water resource supply service of the river basin ecosystem not only serves the interior of the river basin, but also serves parts of the north through the South-to-North Water Transfer Project. As an important part of the surface hydrological cycle, actual evapotranspiration will directly affect the ability of the ecosystem to provide water resources. Under the background of climate and surface environment changes, analysis of the evolutionary trend and causes of actual evapotranspiration in the Yangtze River Basin has important referential significance for the protection of water resources and ecological security in China. Based on the comparison of the accuracy GLEAM_v3.2a, MOD16, GLDAS_Noah2, and ERA_Interim four evapotranspiration data sets, we select the GLEAM_v3.2a data set with the best accuracy to analyze the evolution trend and influencing factors of the actual evapotranspiration in the Yangtze River Basin from 1981 to 2017. The results show that:(1) the evolution of the actual evapotranspiration in the Yangtze River Basin is staged. 1981-1997 was an insignificant decline stage with a decline rate of -0.02 mm/a. The decline area was mainly distributed in the northwest and eastern parts of the Yangtze River Basin. 1998-2017 was a significant rising stage of the whole basin, with an increasing rate of 1.94 mm/a. (2) The decreasing rate of sunshine hours and the increasing rate of vegetation index are the main reasons of periodic changes of the actual evapotranspiration in the Yangtze River Basin. The sudden increases of temperature and wind speed have also played the positive role in the long-term increase trend of actual evapotranspiration in the Yangtze River Basin. (3) Between 1998 and 2017, the water yield of ecosystem in Yangtze River Basin decreased due to the significant increase in actual evapotranspiration. The decline in the western region of the river basin was obvious, and the drought situation was intensified. (4) It is recommended to preferentially strengthen the protection of native forests in the arid areas in the western part of the Yangtze River Basin, and to select tree species with weak transpiration ability such as coniferous trees in afforestation projects, to alleviate the trend of increasing drought.