| Polar Ice-Core, Deep Sea Deposit, Loess are good carriers of the Past Global Changes (PAGES), which contain respectively the global environment changes information of the polar region , ocean , land (where the mankind lived) . In recent years , loess studies on loess-palaeosol sequence have obtained many achievements that attracted attention of the world , however , they are mainly based on the indirect physical and chemical proxies .The pollen studies are fewer and primarily distribute over the Loess Plateau area. So we studied the palaeo-soil of the last interglacial period in Zhaitang Basin of Xishan Mountain Beijing area, where located in the north-east of Loess Plateau, the north of Eastern North China Plain, the northern end of Taihang Mountain , the transition area between warm temperate zone and temperate zone and the intersectant area between CENT1 and CETN2 (CENT: Eastern and Northern Transects of China) .We constructed high-resolution pollen TuPu and paleao-vegetation sequence based on pollen study ,dating by thermo-luminescence and obtaining the age of the sample by interpolation, reconstructed palaeo-vegetation, palaeo-climate and paleo-environment ,then studied climate and environment change pattern by comparative study ,in the last interglacial period in Xishan Mountain Beijing area.The results reveal that pollen belt P1, P2, P3, P4, P5, P6 ,which are from lower to upper, could couple respectively MIS 5e, 5d, 5c, 5b, 5a and the interim from the last interglacial period to the last glacial period. Forest didn't withdraw Xishan Mountain Beijing area in the last interglacial. Deciduous broad leaf forest or coniferous and broad leaf mixed forest which primarily included Carpinus, Ulmus, Quercus, Pinus, Betula existed in warm stages (in interstadials) and forest meadow-steppe or forest steppe which primarily included Pinus, Betulaceae, Rosaceae, Ranunculaceae, Compositae, Artemisia existed in cold stages ( in stadials ) . Climate transited from warm-humid in early stage to temperate-dry or cool-dry, and worsened slowly in fluctuation during the last interglacial period. 5e was the last interglacial megathermal stage ,whose temperature was higher 3 - 5℃ than now and precipitation wasabundant. The climate and environment of 5c was 5a's and 5d's was superior to 5b. Palaeo-vegetation of MIS5e, in Xishan Mountain Beijing area, could be divided 5 stage and suggested climate lied in millennial scale instability and could couple GRIP record, but whose time range, fluctuation range, change feature had own unique and whose optimum combination between heating and moisture was 5el.There was a climate return event during interim from last interglacial period to last glacial period, whose TL age was 78.5 - 72.5 Ka B.P., when forest steppe or open forest steppe lied in Xishan Mountain Beijing aera. In the last interglacial period, the of feature East-Asian monsoon in Xishan Mountain Beijing was that : summer monsoon decreased slowly in fluctuation , winter monsoon went through sub-weak, weak, sub-strong, strong and the combination between summer and winter monsoon was more complicated . Patterns of climate and environment changes during last interglacial period in Xishan Mountain Beijing could couple Polar Ice-Core ,Deep, Sea Deposits, Tibet Plateau and Loess Plateau's, especially had more consistency with Loess Plateau's. It was revealed by the study compared with the South Sea China that Ocean probably was an important factor affected the climate and environment of Beijing area , which mainly affected by summer monsoon and had great effect on climate and environment in interglacial period. In the last interglacial, vegetation, climate and environment were superior to Holocene's and the climatic instability in 5e could find similar change pattern in Holocene Megathermal period in Beijing area, which suggested the climatic instability in interglacial period was probably in generality.
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