Abstract: The Shiyang River,Heihe River,Beida River and Shule River developed 2 Holocene terraces each in the plain area of the Hexi Corridor.Based on ¹⁴C ages from the sediments on the terraces,it is discovered that the lower terraces were formed between 5.57 ka B.P.and 3.15 ka B.P.,the higher terraces were formed between 11 ka B.P.and 8 ka B.P.,and that there was downcutting perod of the rivers from 8 ka B.P.to 6 ka B.P.Comparing the alluvial terraces with the climatic changes in the Holocene,it is concluded that the downcutting period was coincident with the stable warmer and wetter climate,and the aggradation took place when the climate was changing either from drier to wetter or from wetter to drier.