Based on the observation data of five surface flux stations, five kinds of evapotranspiration(ET)products of ET-EB, MOD16, GLEAM, Zhang-ET and GLDAS were verified. Then, the spatio-temporal variation characteristics of surface evapotranspiration in the source region of rivers in Southwest China from 2001 to 2013 were studied by the empirical orthogonal function method. The results show that among the five products, the accuracy of GLEAM is better, and the root mean square error is 23.4 mm/month. The surface evapotranspiration of the source region of rivers in Southwest China has the highest value in summer and the lowest value in winter. From the southeast to the northwest, the surface evapotranspiration of the source region of rivers in Southwest China decreases gradually. From 2001 to 2013, the evapotranspiration of the upper reaches of the Yangtze River and the upper reaches of the Yellow River showed an increasing trend, with the largest increase in the upper reaches of the Yellow River. On the whole, the correlation between specific humidity and surface evapotranspiration is the strongest. However, there are different correlations between surface evapotranspiration and temperature, specific humidity and precipitation in different watersheds. The correlation between surface evapotranspiration and specific humidity is strong in Nujiang River Basin, Lancang River Basin, upper reaches of Yangtze River and upper reaches of Yellow River in spring and autumn, while the surface evapotranspiration of Yarlung Zangbo River Basin, rivers in southern Tibet and Qinghai Lake water system has strong correlation with air temperature. The surface evapotranspiration of the source region of rivers in Southwest China decreases with the increase of elevation and increases with the increase of slope. When the slope direction is southeast and northwest, the surface evapotranspiration is higher.