Abstract: Three cultural ruins at the Mouse Mountain, Lingshan and Hemudu along the south, central and north coast of Zhejiang Province respectively are studied in this paper with the soil samples acquired there. The regional paleoenvironment and sea-level changes during the time of (15 226~5 550) cal. aBP are analyzed on the basis of ¹⁴C dating data and sporo-pollen records. The impact of paleoenvironmental change and sea-level fluctuation on the formation and development of the Hemudu culture is discussed. Our results reveal that during the period of (15 226±256)~(9 778±77) cal. aBP, most of the region is suffered from seawater intrusion and phycophyta was booming. During the period of (9 778±77) cal~(5 550±48) cal. aBP, the region was rather warm and wet, and dominated by wetland marsh. Plants, which favoured a warm and humid environment, dominated with few phycophyta. Two transgressions and two regressions are recognized from the geological records during (15 226±256)~(5 550±48) cal. aBP. The first time of transgression happened in the period from (15 226±256) cal. aBP to (13 600±130) cal. aBP when the climate was mild and semi-humid, and our results suggest that the sea level in that period was higher than the present. Possibly due to the effect of the Younger Dryas Event, the sea level dropped during (13 600±130)~(9 778±77) cal. aBP, and the climate was relatively cold and dry. Climate became warmer again during the period of (9 778±77) cal. aBP to (7 372±36) cal. aBP, which caused the second time of seawater transgression. During (7 372±36)~(5 550±48) cal. aBP, there started the second period of seawater dropping. However, the sea level falling was not big enough to harm the growth of a variety of vegetations. As the result, the Hemudu culture appeared and was prosperously developed until the region was ruined by salt tide and the flooding later on. Changes in the water environment caused by paleoclimate and sea-level fluctuations are the main reason for the rise and fall of the Hemudu culture.