Heq1ing Basin lies in the eeotones of the southeast monsoon and southwest mollsoon.According to the synthetic analysis of the top 8.11m core,we have reconstructed the history of paleoelimatic and environmental changes in the past 30ka.The studys suggsts that Heqing Basin underwent a elimate of cold-wet and warm-dry on a long-time scale.During the last Glaezatlon.perhaps because of the frontal surface,there appeared great preeipitation.responslble for the highest lake level.At the beginning of the Post Glacial.about 14.2kaBP.the basin was cut off.