In this paper the author, based on the analyses of the sedimental features and the paleonto-logic informations in the Mid-lower regions of Changjiang at 18000 yr. B.P., concludes that the temperature was lower at that time than at present and the precipitation was less by then. The wind force was so strong that the loess accumulated on the plains or the hilly regions and the dunes which consist of the older river sand were formed near the lake rims or the bank sides.At the same time, the headward erosion took place along the Changjiang Valley due to the drop of the world sea-level in the full-glacial period. The paleochannel bottom had reached a depth about - 60 m at the north of the present debouch and the water level of main stream in the Mid-lower Changjiang Valley was about 20 - 45 m lower than present, thus provided the Dongting, Poyang and Taihu lakes regions with different erosional plain.