The main contents of this paper is the formation of the Yellow River.To explain that,geomorphological,geochronological,paleomagnetical and geochemistrical methods are used.The major study area is the Hetao basin-Shanxi-Shaanxi Gorge-Sanmenxia basin-Sanmenxia Gorge at the middle reach of the Yellow River,and the miner area is the Xinghai basin at the upper reach of the Yellow River.There are 9 terraces found in Xinghai basin,and the age of the highest T9,T8 and T7 is 200ka,100ka,80ka based on the OSL and ESR dating, respectively.A set of Later Quaternary fluvial-lacustrine stratum is widely distributed in the Hetao basin,Inner Mongolia at the middle reach of the Yellow River.The Haojiayao section in the Togtoh mesa is located in the easternmost part of the Hetao basin,at the gateway of the Shanxi-Shaanxi Gorge,and it formed the second geomorphological platform of the Yellow River.The curves of the lightness of chrominance and the loss of ignition(LOI 950)show the unanimously change bends: from low to high from bottom to top in Haojiayao section.This tendency shows the continued increase of carbonate content in the sediment,and the rise of mineral concentration of lake water which also indicate the closed environment of the lake.The OSL dating indicates that the lacustrine deposition stopped about 100ka.The age of the highest terrace of the Yellow River in the easternmost part of the Sanmenxia basin is 150ka,while the terminating age of the white sand deposition is 200ka which indicated the water leakage.According with the research results of predecessors,the Gonghe Movement is the main cause of the formation of the Yellow River.However,the formation age of the Yellow River at the upper reaches of the Xinghai-Gonghe area(the age is 200ka)and at the middle reaches of the Sanmen Gorge area(the age is 200~150ka)is earlier than that of the Hetao basin(the age is 100ka),and the time of the Yellow River run-through the Shanxi-Shaanxi Gorge is the latest.That is to say that the age of the formation of the Yellow River is 100ka.