A multiproxy record,including grain size,organic carbon and nitrogen,and the stable isotope compositions of organic carbon(delta~(13)C) obtained from Core BDQ06 in the marginal Hoh Xil area,Tibet Plateau,provided evidence for climate change since mid-Pleistocene. The influencing factors and variation characteristics of organic carbon isotope were reviewed. The organic carbon content is controlled by autophyte from lake. The variation of organic carbon isotope is mainly related to the ratio of emergent plant to submerged plant,indicating fluctuation of lake level. Variations of the delta~(13)C can be used to estimate various sources of organic matter in the aquatic environment. The higher delta~(13)C values and lower C /N ratios show the dominance of the submerged plant in the lake,and may reflect higher lake level and more moderate climate. The lower delta~(13) C values is attributed to contributor of emergent aquatic plant and planktont,which used atmospheric CO_2 for photosynthesis,indicating lower lake level and drier climate. Additionally, in certain phases,lower delta~(13)C values corresponding to the C /N ratios of more than 10 may be related to the input of terrestrial higher plant.