Global warming has led to significant changes in the thermodynamic characteristics of lakes on the Tibetan Plateau, resulting in vital impact on lake ecosystem and water quality changes. In this study, continuous observations of lake water temperature and meteorological conditions were carried out in the largest lake—Selin Co, Tibet, the characteristics of intra-annual thermodynamic dynamic of Selin Co and its responding to meteorological conditions are revealed. The results show that Selin Co is a dimictic lake based on continuous observations of water temperature profiles from June 2021 to December 2022. The thermodynamic state can be divided into four phases: winter freezing, spring mixing, summer stratification and fall mixing. Selin Co starts to stratify during the freezing period (mid-March). The melting of the lake ice, the enhanced radiation penetrating the ice and the high salinity resulted in a rapid and stable stratification of the water column under the ice. However, Selin Co did not undergo complete mixing of the water column in the spring, probably due to the salinity gradient, and the mixing phenomenon was confined to the surface 0-30 m, with the bottom waters remaining slowly warmed.The Schmidt Stability ranged from 0 to 520J/m2 in Selin Co. From the characteristics of the thermocline, the daily variation patterns of the thermocline in 2021 and 2022 are very similar, with the maximum depth of the thermocline around 17 m during the summer stratification period. Wind speed and radiation have different driving mechanisms for thermal stratification during different periods. Wind and radiation contribute concurrently to thermal stratification during the formation period, and weakening radiation being the main cause of the disappearance of thermodynamic stratification. Comparative analysis showed that air temperature changes were more variable than surface water temperature, which lagged air temperature by about 21 days. This study conducted the observation and research on the thermodynamic characteristics of Selin Co and its influencing factors for the first time, providing a scientific basis for an in-depth understanding of the changes in water temperature of inland lakes on the Tibetan Plateau and their response to regional climate change, as well as lake modeling research.