Evapotranspiration is a major component of the water budget and energy cycle in the interface of soil-vegetation-air.This paper focused on the effects of climate change and human activity on evapotranspiration(ET)in the Western Songnen Plain of Northeast China by Surface Energy Balance Algorithm for Land(SEBAL)model based on the MODIS data.The results showed that(1)In 2001-2012,the temperature and precipitation of the growing seasons ascended distinctly in the Western Songnen Plain of Northeast China,whereas evapotranspiration was on the decline;ET was positively correlated with temperature and precipitation in the 16-day(interval)scales,while negatively correlated with precipitationin the interannual scales;the increase of ETin the early growing season(May)was attributed to a increasing precipitation in non-growing season(November to March)and a rising temperature in April.However,the increased precipitation in late Spring(April-May)was likely to reduce ET duringthe peak growing season (July-August);(2)Mean daily ETof multi-year growing seasons under different land uses followed a descending order of bare land,cropland and grassland in the Western Songnen Plain of Northeast China where transforms occurred mainly from grassland to cropland and bare land to grassland.Cropland which was once grassland had a lower ETin the early stage of growing season in 2001-2005,and rose to the level of a cropland's in the 2006-2012.After returning farmland to pastures,ET was higher in 2001-2005, and fell below the grassland ETlevel in 2006-2012.The degraded grassland had a lower ETin 2001- 2005 and an approximate bare land ETlevel in 2006-2012 when retrograded into bare land;The ET of grassland after restoration from bare land was low throughout 2001-2012,and 0.2 mm/d below the raw grassland level later;(3)Both climate change and land use change had impacts on ET.Furthermore,climate change had same effect on grassland with land use change,whereas less effect on cropland and bare land.