Abstract: Through composite analysis of CaCO₃ content,colour substitute parameter in the Shagou loess section in the east of Qilian mountain and dating result of ¹⁴C,TL,it is suggested that summer monsoon has five enhancing periods in the last interglacial,reflecting the climatic change of millenium scale from parameter curves,which is well consistent with GRIP record.The climatic instability may be controlled by the change of high latitude ice-sheet and shows the character of the globe climate.In the last glacial,summer monsoon was weak,climate was dry and cold in the long period,which maight be resulted by the uplift of Qinghai-Xizang plateau and the research region was adjacent to the Tengger desert,which made it difficult for summer monsoon to reach in the last glacial,so it showed regional climatic character.

Key words: the last interglacial, desert marginal zone, summer monsoon, northwestern China