Qaidam Basin belongs to the alpine arid inland basin，which is short of water resources and fragile in ecological environment. Evapotranspiration is the main way of water dissipation in the natural ecosystem. The study of its variation characteristics is of great significance to the rational development of regional water resources and ecological environment protection. In this study，the shrub land and alpine meadow in Qaidam Basin were taken as observation stations，and the actual evapotranspiration was calculated by using the flux data observed by eddy covariance in 2020. The change characteristics of actual evapotranspiration of different underlying surfaces in different time scales were analyzed，and the correlation between meteorological factors and actual evapotranspiration was explored. The results showed that：（1）The evapotranspiration process of shrub land and alpine meadow mainly concentrated in the growing season，and the distribution was normal，but the variation range was different，and the actual daily and monthly evapotranspiration of alpine meadow was greater than those of shrub land. Among them，the average daily evapotranspiration of shrub land was 0. 48 mm，and that of alpine meadow was 1. 28 mm. The evapotranspiration of shrub land peaked at 40. 47 mm in August and evapotranspiration of alpine meadow peaked in July at 88. 92 mm.（2）For different underlying surfaces，the variation trend of air temperature and soil temperature were roughly the same，but the vapor pressure deficit and wind speed had some differences. The actual daily evapotranspiration was significantly correlated with air temperature，soil temperature，and vapor pressure deficit，but not much related to wind speed，and the sensitivity of evapotranspiration to meteorological factors was different in each season. In addition，the evapotranspiration of alpine meadow was significantly correlated with the soil water content.（3）The variation characteristics of water consumption of different underlying surfaces showed that the underlying surface of shrub land was mainly characterized by water consumption in each month，and the water consumption was most serious in July and August. The underlying sur‐ face of the alpine meadow was mainly characterized by water absorption in April，June，and November，and reached the peak of water absorption in June. The underlying surface of the alpine meadow was dominated by water consumption in other months，with the largest water consumption in July. This study discussed the actual evapotranspiration characteristics of shrub land and alpine meadow in Qaidam Basin，in order to provide certain reference for the study of water cycle in this area.