Many water-saving projects have been initiated in the typical alpine irrigation district in Tibet, which resulted in dramatic changes to the hydrothermal conversion process. There is an urgent need to fully understand the hydrothermal transport process and to clarify the mechanism under which agricultural hydrology evolves in the alpine irrigation district of Tibet. This study selected highland barley field, oat field, wasteland (Natural herbage field without irrigation) in Pengbo irrigation district of Tibet as study objects to study soil water and heat dynamics and soil water balance. Observed water and temperature data were used to calibrate and validate simulations of the HYDRUS_1D model for 2019 and 2020, respectively. Simulations of soil water and temperature were in good agreement with the measured values, with determination coefficient of 0.69–0.91.This study proposes a set of hydrothermal parameters to fill the gap in the hydrothermal research of Tibet. The results showed that the variation of soil temperature was approximately sinusoidal, with a lag effect. The temperatures of the 0–20 cm and 30–50 cm soil layers lagged by about 1–2 h and 3–5 h, respectively. The highest rate of soil temperature increase occurred from the initial growth period to the rapid growth period during which the soil temperature of each layer increased by an average of 2 °C, however, the soil temperature in this period was not the most suitable for crop growth. Soil evaporation of highland barley field, oat field, and wasteland during the growth period accounted for 20 % – 29 %, 20 % – 29 %, 10 % – 18 % of the rainfall and irrigation, whereas transpiration accounted for 33 % – 43 %, 42 % – 50 %, and 36 % – 57 %, and percolation accounted for 42 %, 35–39 %, and 16–45 %, respectively. Implementation of water-saving projects resulted in reductions in irrigation volume and percolation rate. This study can provide a reference for clarifying the hydrothermal transport process and allocating agricultural water resources in the alpine irrigation district of Tibet.