Four sediment cores were collected at three sites from Pumoyum Co, Southern Tibet. Sedimentation age was constructedby using ²¹⁰ Pb and¹³⁷Cs measurements from one short core. Environmental proxies such as total organic carbon, inorganic carbon,grain size and element concentrations were analyzed for upper parts of other three cores. The proxies from different cores werecompared and then environmental changes during the last ca. 200 years were discussed. Although proxies changing trends of differentcores are similar, obvious differences appear in both detailed variations and proxies values, probably resulting from different waterdepth, underwater landform conditions and distances to rivers among the sites. Environment condition in this area was stable before1900AD, but it fluctuated during 1900-1940AD with enhancement of surface erosion and increased sedimentation rate. Remarkablechanges took place at about 1940AD, showing that the temperature increased greatly, grain size of sediments became coarser and thelake was in the state of shrinkage, indicating environment in this area changed to a warm/dry state.