Terrestrial evapotranspiration (ET), composed of soil evaporation and plant transpiration, is the main mode of water dissipation in the natural ecosystems. In general, ET returns about two thirds of the annually terrestrial precipitation to the atmosphere on the global scale, and the ratio can reach as high as 80% in arid areas. As a result, accurate knowledge of ET is crucial to understand the water budget as well as its effect on ecosystems. This is particularly important for water resources management and eco-environmental protection in arid regions. Compared with ground-based ET measurements recorded by sparse flux towers, satellite remote sensing (RS) is a suitable tool to map regional ET patterns in a temporally and spatially consistent manner, yielding a series of RS-based ET models with varying mechanisms and degrees of complexity. Considering the sparse distribution of meteorological observations in the Northwest of China, we adopted the surface temperature-vegetation index (TVX) method in this study to estimate daily ET in Qaidam Basin from 2011 to 2019. Uniquely, the theoretical boundaries of the TVX feature space were determined pixel by pixel based on the surface energy balance principle, so ET could be mapped for regions with complex topography in a spatially consistent manner. Then a simple dual-source ET framework was used to partition evapotranspiration into soil evaporation (E) and plant transpiration (T), and finally the water consumption efficiency of natural ecosystems was evaluated by further partitioning E into soil evaporation over bare land and soil evaporation beneath the canopy. All the above schemes were demonstrated with Terra Moderate Resolution Imaging Spectroradiometer (MODIS) products. Results show that the annual ET of Qaidam Basin from 2011 to 2019 decreased at first and then increased, with an average value of 188.75 mm. As for seasonal variations, ET from April to September accounted for 80% of the annual ET with the peak value arising in June or July. Influenced by the spatial patterns of precipitation, the ET presents an obviously decreasing trend from southeast to northwest and from the surrounding mountains to the interior of the basin. Local high ET values in the interior of the basin are mainly distributed around the rivers, lakes, and springs. The annual average E and T in the recent nine years is 171.06 mm and 14.26 mm, respectively. Although the seasonal variations of both E and T follow a trend similar to sinusoidal curves with the peak values observed in summer, the peak of the latter appears one month later than that of the former. In terms of spatial distribution, soil evaporation shares patterns consistent with total ET, but plant transpiration is mainly observed in the southeast of the basin, showing a semi-ring structure. The annually total water consumption of terrestrial ecosystems in the basin is 43.094 billion m3 on average. The corresponding proportion of high-efficiency, medium-efficiency and low-efficiency water consumption is 6.55%, 52.57% and 40.88%, respectively. Due to the extremely low fractional vegetation cover of Qaidam Basin, the amount of water consumption with high-efficiency is much lower than the other two. However, when considered water consumed by bare land and dense canopy, the water consumed by dense canopy per unit area is 297.83 mm, which is much higher than that consumed by bare land. In conclusion, this study reveals the water consumption efficiency of ET in the whole Qaidam Basin in a temporally and spatially consistent manner, which provides important scientific support for ET-based water resources management.