The lakes of the Qinghai-Tibet Plateau (QTP) are a crucial component of the water resources of the "Asian Water Tower", possessing significant value for sustaining regional water cycles and ecosystem services. Studying the past evolution of lake level on the QTP can reveal the potential links between climatic and hydrological variability, thereby facilitating the prediction of future hydrological changes in the region. In this study, we use the lake sediments of Gongzhu Co (GZC) on the southwestern QTP to reconstruct hydrological changes since 29 cal ka BP, based on multiple proxies including leaf wax n-alkanes and elemental geochemistry data. During the study interval, the lake level fluctuated substantially, which can be divided into four stages: 1) Stage I (29-17.9 cal ka BP): Low lake level with minor fluctuations; 2) Stage II (17.9-7.6 cal ka BP): Maximum and stable lake level; 3) Stage III (7.6-6.3 cal ka BP): Rapid lake level fall; 4) Stage IV (6.3 cal ka BP-present): Intermediate lake level with fluctuations. It suggests that the cold and arid climate, dominated by the westerlies, was the main cause of the low lake level of GZC during the early stage of MIS 2 (29-17.9 cal ka BP). During the last deglacial (17.9-15 cal ka BP), intense glacial meltwater influx led to the rise of the GZC lake level. Increased precipitation driven by an intensified ISM sustained the high level of GZC during the last deglacial to mid-Holocene (15-7.6 cal ka BP). Subsequently, the long-term precipitation-evaporation balance governed the variations in lake level. Our results serve as an appropriate analog for regional lake level responses to ongoing warming, offering valuable insights into the future evolution of lakes across the QTP.