Mapam Yumco,located in the southwest of Tibetan Plateau,is one of the ideal areas to study the evolution of Indian monsoon.A 4.69 m long core was obtained at a depth of 75 m at Mapam Yumco using a piston sampler.The core age was determined by ~(210)Pb and AMS ~(14)C dating.According to the element content (XRF scanning),total organic carbon(TOC),total inorganic carbon(TIC) and total nitrogen(TN) et al,lake environment changes since 14 cal.ka B.P.were reconstructed.The results showed that during the deglaciation period (14 ~ 12 cal.ka B.P.),TOC and TIC showed that the lake environment was relatively warm and wet on the whole.12.0 ~11.4 cal.ka B.P.,runoff was significantly weakened under the influence of the YD event.In the Early and Middle Holocene(11.4~3.4 cal.ka B.P.),the overall environment of the lake area was still warm and humid,and the climate fluctuated.There were two cold events(10.2 ~9.8 cal.ka B.P.and about 8.2 cal.ka B.P.),and 7.4 ~6.6 cal.ka B.P.,showing a warm period.In the Late Holocene (3.4 ~0 cal.kaB.P.),the lake environment as a whole tended to be arid,accompanied by two periods of relative humidity (2.6 ~2.0 cal.ka B.P.and 1.4 ~1.0 cal.ka B.P.).The changes in the environment of Mapam Yumco show that since the late glacial period(14.0 ~3.4 cal.ka B.P.),the Indian monsoon brought more precipitation and the glacier melt water had increased under the influence of solar radiation,and the environment in the lake area is relatively humid,which is conducive to the survival of endogenous organisms on the whole.In the Late Holocene(3.4 ~0 cal.kaB.P.),the solar radiation in the Northern Hemisphere decreased in the summer,the Indian monsoon weakened and lake environment developed towards aridification.