Ejinaqi is far from ocean and located in Asian hinterland where the atmospheric circulation is hindered by high mountains. Ejinaqi is controlled by this geographic setting, especially the rapid uplift of Qinghai-Tibet Plateau since the late Quaternary, which undoubtedly influences the climate and environment in Ejinaqi. One of our objectivcs is to establish the palaeoclimatic evolution sequence and to reveal the character of palaeoclimatic changes since the late Quaternary through comprehensively analyzing physical, chemical and biological proxy of sediment in Juyanhai lake. The sediment character, pollen and ostracode assemblage, minerals, and geochemical elements of 42.5m long core in middle-west of Gaxun Nur and of JYH-E section in Quyanhai indicate that there are 8 climate stages and the climate was mainly warmer and cool or warmer with obvious fluctuating from dry to wet since middle-Pleis-tocene. It was cooler and relative wet before 218. 3 kaBP; From172. 8 kaBP to 218. 3 kaBP, the climate was cooler and relative wetter and the lake expanded to a deeper lake; the climate turned to be colder or cooler an dry from 172. 8 to 93.4 kaBP; from 93. 4 kaBP to 67. 4 kaBP, the lake shrank to be a shallow lake, showing the climate probably was mild with little humidity; from 67.4 to 5.4 kaBP, the salinity of the lake increased and the climate was cooler and relative dry; from 54 kaBP to 48. 9 kaBP, the climate was warmer and wetter; the climate was cool and dry from 48. 9 kaBP to 42. 6 kaBP; after 42. 6 kaBP, the climate alternated with warmer-wetter and cooler-dry.