A section of lacustrine deposits of the Late Pleistocene was discovered in the Buqu Basin of the Changjiang (Yangtze) River source. The lacustrine deposits have U-series ages of 88.9 ka to 56.2 ka. Based on the U-series dating and sporo-pollen analysis, this paper presents a discussion on the paleovegetation and paleoclimate of the Buqu Basin and its adjacent regions during the interval 88.9~56.2 ka BP of the Late Pleistocene. A preliminary study shows that the evolution of vegetation and climate has experienced features of the late stage of the last interglaciation through the early stage of the last glaciation to the middle stage of the interglaciation of the last glaciation.