Based on the China snow depth time series data set and high resolution ground meteorological element driven dataset，this study analyzes the spatial and temporal variation of snow depth on the Qinghai-Xizang （Tibetan）Plateau by watershed and elevation gradient during the 1980-2020 snow season considering different river basins and elevation gradients. Additionally，the study investigates the response of snow depth to climate change in the context of hydrothermal factors. The results show that：（1）Spatial difference in snow depth on the Qinghai-Xizang（Tibetan）Plateau was obvious，showing a distribution pattern of high in the west and low in the east，and greater in the high-altitude mountain areas than in the basin plains，with the average snow depth in the high-altitude mountain areas generally greater than 10 cm. The average snow depth decreased at a rate of 0. 25 cm/decade，64. 74% of the regions showed a declining trend，with statistically significant decreases in 29. 09% on the Qinghai-Xizang（Tibetan）Plateau during the snow season from 1980 to 2020.（2）There is a clear vertical zonation of snow depth and its trend as influenced by altitude. Below an altitude of 4. 2 km，average snow depth increased with elevation. Between 4. 2 km and 4. 8 km，average snow depth decreased as elevation rises. Above 4. 8 km，average snow depth again increased with elevation. A decreasing trend in snow depth was observed across all elevation bands，with the rate of decrease initially increasing and then decreasing with elevation，exhibiting a threshold at approximately 5. 0 km. The most rapid decrease in mean snow depth［3. 36 cm·（10a）-1］ occurred in the 5. 0~5. 2 km elevation band. The interannual variation of mean snow depth exhibited a pronounced altitude-dependent pattern，the rate of snow depth reduction was significantly higher at higher elevations than at lower elevations，especially at 4. 8~5. 5 km.（3）Climate change on the Qinghai-Xizang（Tibetan） Plateau is ‘warmer and wetter’ overall，but ‘warmer and drier’ in the north-west and south during the snow sea‐ son from 1980 to 2020. However，there are watershed differences and elevation differences in the response of snow depth to climate change. Specifically，in the Nujiang，Ganges，Amu Darya，and Indus River basins，the warming and aridification of climate conditions have contributed to a reduction in snow depth. Conversely，temperature has a more pronounced effect on snow depth in the Yarlung Tsangpo River，the interior plateau，as well as the Yangtze River basins，the Qaidam Basin，and the Tarim Basin. Additionally，precipitation plays a more significant role in influencing snow depth in the Yellow River，Heihe River basin. In regions with altitudes below 3. 5 km，climate conditions characterized by warming and aridification have led to a reduction in snow depth. However，in areas with altitudes above 3. 5 km，temperature has a more pronounced influence on snow depth. The altitude-dependent warming of temperature accounts for the altitude-dependent reduction in snow depth.