The Tibetan Plateau is a sensitive region to climate changes controlled by interactions of large-scale atmospheric circulations, including the East Asian monsoon, Indian monsoon and mid-latitude westerlies. This paper presents a high-resolution humidly reconstruction over the past 2000 years from the sediment of Yamzhog Yumco Lake (28°27'?29°12'N,90°08'?91°45'E; altitude in 4440m a.s.l.), a representative inland lake located at southern Tibetan Plateau,China. A suite of 50cm-long cores (29°10'40"N,90°32'25"E; 4440m a.s.l. and 3.2m in depth) was drilled from the northwest part of the lake using Russian drill in 2013. The cores were mainly composed of clayey silt, intercalated with silt, with minor fine sand and medium-grained sand. 50 grain-size samples were sampled at lcm intervals. 19 samples collected from the upper portion of the core were used in ~(210)Pb dating and two plant materials from the lower portion of the core were dated by AMS ~(14)C dating method. According to the analysis, an age-depth model was established by AMS ~(14)C dating and ~(210)Pb measurements for the past 2000 years. The study on environmentally sensitive grain-size population and comparison with modern hydrologic data implied the clay fraction (7 ?lOmum) percentage could be used as a proxy for lake-level change during the past 2000 years. Then, the humidity changes during the past 2000 years in the southern Tibetan Plateau have been reconstructed based on the grain-size recorded from Yamzhog Yumco Lake core,including the clay fraction (7~10mum) percentage, grain-size population, grain-size frequency curve and grain-size parameters. The variation of humidity revealed by the reconstruction indicated that there were four periods during the last 2000 years. From 100 to 820 A.D., the sediment sizes were finer, suggesting a relatively high lake level and effective moisture,and a moderately wet and cool period corresponding to the Dark Age Cold Period (DACP). Subsequently, a relatively low lake level and effective moisture prevailed between 820 A.D. and 1200 A.D., as inferred by the coarser sediment sizes. And a dry climate might have occurred in the studying area during the Medieval Warm Period (MWP). During 1200 ?1910A.D.,the lake level rising and effective moisture increase under a wetting climate, those were reconstructed on the basis of the fining of sediment. The climate was wetter in this period, which could correspond to the Little Ice Age (LIA). Moreover, the wettest phases occurred on about 1200?1320A.D.,1400- 1550A.D. and 1780 ?1900A.D.,which might correspond to the three coldest phases of the Little Ice Age. Since the 20th century, the lake level quickly lowered and a dry climate prevailed in the studying area during the 20th century warm period (CWP). Two views were obtained by comparison with the solar insolation,Northern Hemisphere temperature proxy and Asian monsoon index from other regions. (1) During the last 2000 years the humidity changes recorded by the grain-size in Yamzhog Yumco lake was in broad consistent with the records from the Tibetan Plateau and surrounding areas, but the amplitude and duration of regional phases were different. (2) The pattern of climate change in the southern Tibetan Plateau during the past 2000 years probably was warm-dry and cold-wet types, which might be in close relationship to the temperature and solar insolation. Moreover, the well dated, high-resolution grain-size record from lake sediments could remedy the lack of studies on moisture records in the southern Tibetan Plateau during the past 2000 years. Therefore, it is of great significance to better understand the mechanisms of the climate change in the high elevation of monsoon areas over the past two millennia.