| Based on the qinghai-tibet plateau the thesis analysed many indicators of a 106-meter-long lake sediment of BDQ0608 core, established the date of BDQ core using magnetic geomagnetism,and tried to establish the time scale of the BDQ core,by contrast of the suspended material of 0.2-7.5μm which was more sensitive to the change of water power and deep-sea oxygen isotope curve.The author established the Hoh Xil region's environmental evolution sequence through a comprehensive analysis of proxy climate indicator. According to geological survey analysis and pollen concentration in contrast to TOC and MS, the author viewed that they had a good correlation:the pollen concentration was very high,TOC curve had a high value. Later,the percentage pollen diagram was divided into four pollenassemblage zones, with seven subzones when necessary, based on stratigraphically constrained cluster analysis, according to the relative content of various types of relationships and changes in the concentration of pollen diagram characteristics of the percentage of pollen diagram in the coniferous forest, broadleaf forest, herbaceous plants and shrubs.730-700ka, there was a sudden drop in dry herbaceous plants such as Artemisia, Ephedra, while other dry herbaceous Ranunculaceae, Zygophyllaceae, Polygonaceae had disappeared.This sub-zone Picea had increased significantly.At this time the total concentration of pollen was up to the maximum of this profile 159,077.46 grain/gram. Pollen assemblage changes directed that a semi-desert steppe retreated, whereas,the forests on the surrounding mountain began to increase.Pollen temperature index decreased and humidity index increased.Pollen indicated that climate became cool and wet gradually.700-455ka, Pollen assemblage changes directed that a semi-desert steppe was still expanding, but forest was degenerate continuously on the mountains near the lake. Pollen temperature and the humidity index decreased.Vegetation and pollen climate index changes directed that the climate became warmer and drier.455-375ka, Chenopodiaceae and Artemisia decreaseed in the pollen assemblage, Picea increased significantly,and forests were developed,semi-desert steppe degenerated slightly. 375-345ka coniferous spruce genera and reduction, the core of a running, and herb's chenopodiaceae and artemisia content is higher, the other representatives of thistles and drought in certain ephedra genera and peak. Thus, the coniferous forest may have deteriorated, vegetation types in grassland vegetation, dry climate.345-265ka, arid herb as Artemisia and Chenopodiaceae in the pollen assemblage was up to the maximum, and forest was degenerate,desert steppeland had the further development with an arid climate.265-210ka, coniferous forest of Pinus and Picea reached the maximum value of the pollen diagram, coniferous forests further significant expanded and reached the maximum, the climate was even colder and weter. 210-160ka, Chenopodiaceae and reduced in pollen assemblage, the coniferous forest of Pinus and Picea increased sharply, desert steppe retreated, coniferous forest prevailed, and the weather became cool.160-25ka, pollen assemblage was dominated by desert steppe plant including Artemisia and Chenopodiaceae, the climate was mainly warm and dry.To study the area size of the core, comprehensive, magnetic susceptibility TOC index curve is relatively good correspondence, there are some differences, but the difference is unavoidable, because each index controlled different factors. Through the pollen of vegetation restoration and climate with high resolution, combined with other substitution indexes, can achieve a high contrast the accuracy.
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