The hydrothermal changes of the active layer directly affect the water energy balance exchange process between the permafrost layer and the atmosphere, which in turn affects the hydrological cycle and surface energy cycle in the cold region. Based on the soil hydrothermal and meteorological data of the Tanggula area of the Yangtze River source from 2020 to 2021, the SHAW model was used to simulate the soil temperature and humidity to calculate the characteristics of soil water balance and surface energy balance. The results showed that: (1) the simulation effect of soil temperature was better than that of soil moisture, the NSE (Nash efficiency coefficient) of temperature simulation was≥0.94 and R2≥0.98, and the mean values of soil moisture simulation NSE were 0.61 and R2 were 0.8, indicating that the simulation results had a certain degree of reliability; Soil water storage and surface water accumulation constituted water expenditure, accounting for 36%, 49.1%, 14.4% and 0.5%, respectively. (3) The surface energy balance changes alternately in the cold and warm seasons, the net radiation, latent heat flux and soil heat flux increase in the warm season and decrease in the cold season, and the sensible heat flux shows an opposite trend, and the monsoon activity and freeze-thaw action become the key factors affecting the net radiation budget. During the simulation period, the average daily net radiation was 46.48W/m2, 32.7% was converted into sensible heat flux, 65.1% was converted into latent heat flux, and the soil heat flux accounted for only 0.3%.