Abstract: Terrestrial evapotranspiration (ET) connects land water cycle with land energy cycle. Analysis of the spatio-temporal of ET in Huai River basin helps us understand the response of water cycle in Chinese climate transition zone to global climate change and provide some valuable information for prediction of the change of water resource in that region in the future. Based on water balance model in Huai River basin, this study validated the accuracy and applicability of ET data from Global Land-surface Evaporation: the Amsterdam Methodology (GLEAM) using hydrological data. In addition, we also analyzed the interannual spatio-temporal variation of yearly and seasonal ET and the annual cycle of the monthly and daily ET in the Huai River basin during the period from 1980 to 2011 using GLEAM ET data. Results showed that: 1) Compared to the observed precipitation, the precipitation estimated by GLEAM ET data had lower mean relative error (MRE 8.0%) and the high correlation coefficient (0.94); The GLEAM data showed a high capacity of reflecting the magnitudes and spatial pattern of basin-scale ET in Huai River basin; 2) The mean annual ET of Huai River basin was 673 mm during the period of 1980-2011; 3) GLEAM model showed that the spatial variation of mean annual ET value ranged from 528 to 848 mm during the period from January 1, 1980 to December 31, 2011 over Huai River basin, which had a significant difference in spatial patterns; GLEAM model also showed that spatial patterns of mean annual ET decreased from the southwest to the northeast part of Huai River basin and that the mean annual ET in the southern region of Huai River was greater than in the northern region of Huai River; The mean seasonal ET had similar spatial pattern with the mean annual ET using the GLEAM ET data over the Huai River basin; 4) the domain-averaged annual ET in Huai River basin varied from 588.6 to 767.8 mm and showed a prominent increasing tendency for the period of 1980-2011; The GLEAM ET data showed a strong seasonality of ET in Huai River basin with the maxima in August and the minima in December; Among four seasons, the summer ET was the largest with the value of 272.0 mm, followed by the spring(191.4 mm) and autumn (144.3 mm); The smallest value was 65.0 mm in winter; 5) Spatial distribution of annual change rate of ET during 1980 to 2011 in Huai River basin every 10 years based on grid scale for all of Huai River basin was dominated by the change rate of ET in spring, followed by that in summer and autumn. The effect of ET changing rate in winter on annual ET was quite weak. Annual ET in most area over Huai River basin had an increasing tendency. Overall, this study can provide valuble information for monitoring and forecasting extreme hydrometeorological events, such as flood and drought. It also can provide decision-making reference for water resource management in Huai River basin.