Abstract: This paper focus on the main sand-fixing vegetation Caragana microphylla in the Horqin Sandy Land, China. Based on routine meteorological data in growing seasons between 2016 and 2017, the actual evapotranspiration its components of Caragana microphylla community were simulated by Shuttle-Wallace model. Simulated Evapotranspiration values were compared to the eddy covariance method. During 2016 growing season, the evapotranspiration of the community C. microphylla were founded to be 345.4 mm, which consisted of 93.8 mm of evaporation and 251.6mm of transpiration. It means that evaporation accounted for 27.2% of evapotranspiration. During 2017 growing season, the evapotranspiration of the community C. microphylla were founded to be 325.2 mm, which consisted of 83.8 mm of evaporation and 241.4 mm of transpiration. It means that evaporation accounted for 25.8%. The simulated ET was close to the eddy covariance observed ET at the 30 min time-scale. The simulation performance of the S-W model for clear days was better than that for cloudy or rainy days. In the period of continuous drought and after precipitation, water consumption and transpiration of C. microphylla was different significantly. During drought period, C. microphylla maintained lower transpiration and appeared "midday depression". However after precipitation, the "midday depression" was disappeared, and transpiration was increased significantly. At last, we get conclusion that C. microphyllaa's evapotranspiration was mainly affected by vapor pressure deficit.

Key words: evapotranspiration partitioning, S-W model, drought, precipitation