Evapotranspiration(ET)and its response to global change are one of the focuses of global change research and study on variations in evapotranspiration can provide credible data for regional water resources planning and ecological environment improvement.Based on MODIS-ET data,spatial-temporal variation patterns of evapotranspiration in the Loess Plateau in Shaanxi-Gansu-Ningxia Region during 2000-2012 were analyzed. Meanwhile,the influencing factors of the ET's variations in the Loess Plateau in Shaanxi-Gansu-Ningxia Region were analyzed by observation data of the meteorological stations and correlation coefficients calculation of ET to climate elements.The results showed that:(1)The average of ET in the Loess Plateau in Shaanxi-Gansu- Ningxia Region increased rapidly in 2000-2002 and peaked in 2003(378.6 mm),and there was a downward trends in evapotranspiration in 2003-2006,after 2006 evapotranspiration showed a slow upward trend.(2) The spatial distribution pattern of annual ET was apparently various.ET increased gradually from the northwest to the southeast,and ET of southern forest regions,such as Liupanshan Mountain,Ziwuling Mountain and Huanglong Mountain were higher than that in other parts of the Loess Plateau in Shaanxi-Gansu-Ningxia Region. The maximum seasonal value of the ET lay in summer,then followed by spring,and the lest ET was in autumn and winter;the spatial distribution pattern of seasonal ET was basically the same as annual pattern.(3) Different land use/cover types had different contribution to the ET distribution in the Loess Plateau in Shaanxi- Gansu-Ningxia Region.The highest contribution rates were made by grasslands and croplands,closely followed by closed shrubland and open shrubland,while the evergreen needle leaf forest and woody savannas contributed less for ET distribution.(4)The influencing factors of ET were as the following:ET in main part was positively correlated with forceful factor,wind speed affected the ET significantly.The thermodynamical factor mainly negatively correlated with ET changes.The air temperature was negatively correlated with ET in most areas whereas sunshine hours in the less region with negative correspondence with ET than air temperature.Besides,it can be found that moisture condition like precipitation and relative humidityboth had strong positive effect on the ET.