Nam Co is the biggest and highest lake (4718 m a. s. 1. ) in the central Xizang (Tibet) Plateau. The survey of level shows that there are 6 lake terraces and highstand lacustrine sediments from 48 m to 139. 2 m above lake level. Age results of U-series and 14C indicates that the highstand lacustrine sediments, lake terraces of Nos. 6, 5, 4, 3, 2 and 1 were formed in ca. 115. 9~71.8ka BP, 53.7 ka B. P. , 41. 2 ~ 39. 5 ka BP, 36. 1 ~35. 2 ka BP, 32. 3 ka BP, 28. 2~11. 2 ka BP and 11. 2~4. 2 ka BP, respectively. Based on the data of age results, terraces, lacustrine sediments and sporopollen analysis, the paleovegetation, paleoclimate and lake-level fluctuation of Nam Co since approximate 120 ka BP are discussed in this paper. The change of paleovegetation, paleoclimate and lake-level fluctuation of Nam Co since the Last Interglacial Stage can be divided into the five stages: (1) In 116 ~ 78 ka BP, lake-level fluctuated between 140 m and 88 m above lake level. The climate was warm and slightly moist. The vegetation was forest-steppe and steppe with sparse-forest. (2) In 78 ~ 53 ka BP, lake-level strikingly dropped and fluctuated between 48 m and 36 m above lake level. The climate was colder and drier than that earlier. The vegetation was steppe with a few trees. (3) In 53~32 ka BP, lake-level fluctuated between 15 m and 28 m above lake level. The climate was warmer and wetter than that of the present and there were 3 stages of warm climate corresponding to the lake-terraces of Nos. 5, 4 and 3. The vegetation was forest and forest-steppe. Particularly, in the period of 36 ?35 ka BP, coniferous and deciduous broad-leaf mixed forest occurred. It shows, in the period, the climate was the warmest and wettest during the Last Glacial Stage and also was warmer and wetter than that of the present. (4) In 32 ~12 ka BP, lake-level strikingly dropped and fluctuated between 17m and 12m above lake level. The climate was cold and dry. The vegetation was steppe or steppe with sparse trees. The lowest lake-level is 8 m above lake level in the period. (5) In 11. 8~4. 2 ka BP, lake-level fluctuated between 2 m and 9 m above lake level. The climate was warm and wet. The vegetation was forest and steppe with a few trees. Especially, coniferous and deciduous broad-leaf mixed forest occurred during 8. 4 ~ 4. 2 ka BP and the climate is the warmest and wettest during the Holocene. The lowest lake-level is under present lake level in the period. A comparison of the climate change and lake-level fluctuation of Nam Co with the data of oxygen isotopic curve from the Guliya ice core in the West Kunlun Mountains and the ice core of GRIP2 shows the cooling and warming change of climate in the Nam Co area correspond to the climate change of the Tibet Plateau and the northern hemisphere. Especially, the striking lake-level dropping revealed by lake terraces formed is broadly associated with the Henrich events.