Based on a great deal of the data from C14 dating measurement and analyses of sporo-pollen combinations, this paper dealt with the evolution tendency of palaeoclimatic environment in the west loess plaleau since the late plaistocene. It was found that in the area north of the line going from Lanzhou through the southern Jingyuan to Huanxian County,the semi-arid climatic environment under the modern steppe and the desert steppe might have been created basically since the late pleistocene and it is drier at p...