Abstract: Ten spore-pollen zones have been distinguished from the Quaternary sedi-ments of Taihu region,reflecting ten phases of the paleovegetation successionsince the middle Pleistocene of Taihu region.These phases are as follow inascending order:deciduous broad-leaved and coniferous mixed forest and deciduousbroad-leaved forest containing evergreen broad-leaf tree of the middle Pleistocene,reflecting the climate changing from cold and dry to warm and moist;coniferousand broad-leaf mixed forest,evergreen broad-leaf and deciduous broad-leavedmixed forest and Pinus and Cupressaceae forest-grasslands with a few of Piccaand Abies of the late Pleistocene,indicating cold and dry,warm and moist andcold and dry three climate phases;coniferous and broad-leaf mixed forest,broad-leaf and coniferous mixed forest-grasslands,evergreen broad-leaf forest、conife-rous and broad-leaf mixed forest and limnetic vegetation mainly consisted ofConcentricystes and Potamo eton Of Holocene,reflecting that the climate hasundergone five phases:cool and moist,temperate and dry,hot and moist,temperate and dry and warm and moist,the last one nearly being equal to theclimate of present.The late Pleistocene had the lowest temperature,7—8℃lower than that of present.The hot and moist climate of the middle Holoceneresulted in the sea level rising and Taihu Lake was transgressed by sea waterand became a lagoon or a gulf.