Zigetang Co, located on the central Tibetan Plateau, is a meromictic saline lake. A 96-cm-long core(ZGTC A-1)wastaken from Zigetang Co(the water depth 25m) in summer 2006. The age of the upper 9. 25cm(since 1890AD) of the core wasgot through CIC model of ²¹⁰Pb. The ¹³C during the past 60 years had good correlation with the average temperature in Naqu Sta-lion,which indicated that it was mainly controlled by average temperature in a year. When the annual mean temperature was high-er, the ¹³C value in the sediment became heavier and vice versa. In Zigetang Co, the main factor controlling the ¹³C was theCO₂exchange between lake water and atmosphere. Seasonal variation of Ca²⁺and dissolved inorganic carbon(DIC) indicated thatthe calcium carbonate(mainly composed of calcite and aragonite) mainly precipitated in summer. The dissolved CO₂ in the lakewater escaped into the atmosphere due to the relatively high temperature in summer. When the average temperature in a year washigher, the escape of CO₂ into the atmosphere became larger due to the shorter frozen time on the lake surface in winter and higherwater temperature in summer, which induced the ¹³C of the dissolved inorganic carbon in the lake water was more positive, so dothe ¹³C in carbonates.