Abstract: The lower reach of Weihe River in the south plain of Laizhou Bay is one of the most typical areas of salt-water intrusion in China． The occurrence， development and movement pattern of the salt-water intrusion are closely related to the sediments composition in the palaeochannel of the Weihe River．A detailed investigation including data collected from more than 100 geologic drillings， analyses of sediment grains and microfossils, 14C and thermoluminescence age data from two typical bores has been conducted to study the distribution and sedimentary characters of the palaeochannel since the Late Pleistocene． The relationship between sedimentary structures and burial characters of palaeochannel and salt-water intrusion are then discussed．The results of this study have suggested that the sediments in the paleochannel can be divided into 4 sedimentary cycles according to grain size．The calculated depth of sand sediment indicates that the thickness of sand layer is about 30 to 50m in the eastern part but lass than 20 m in western par t of Weihe River，an d the continuity of sand layer is also better in the eastern part than in the western part．The difference of sedimentary characteristics lead to the salt-water intrusion earlier in eastern part and became slow recently， while the salt-water intrusion in western part occurred since late 1970’s mainly due to the human exploitation of groundwater and the intrusion distance of salt-water through the paleochannel can reach to 9 or 10km ．The study of paleochannel sediments and its relation to salt-water intrusion can provide scientific reference to ground water exploration and the control measures of salt-water intrusion．