According to a multi-proxy reconstruction in Caotan Lake using pollen, phytolith records, and the data of LOI, grain size, and susceptibility, four pollen-assemblage zones were distinguished from 96 cm to the top of the sequence (Figure 2). In Zone I (99–66 cm; 4500–2500 cal. aBP), remarkable lowest pollen percentages of arboreal and aquatic plants, concentrations of total pollen, aquatic plants, Polypodiaceae spore, trees, shrub and herb, and relatively lower values of fan-shaped and square phytolith and higher values of elongate and point-shaped phytolith as an indicator of a cold and dry climate [Lu et al., 1996] suggested a dry climatic condition, which was not favorable for the accumulation of peat. Since 2500 cal. aBP, higher concentration of total pollen, aquatic plants, shrub and herb and arboreal pollen, and high content of fan-shaped phytolith showed that the climate became wetter than in Zone I and the wetland developed with abundant freshwater aquatic plants, which contributed to peat accumulation. Nevertheless, alternate periods of humid and dry climate occurred during that period. Concentration of total pollen, aquatic plants, shrub and herb and arboreal pollen were at the second highest values in Zone II (66–42 cm; 2500–1800 cal. aBP). Secondly, high content of Phragmites fan-shaped phytolith, as indicators of a warm and humid climate, and higher susceptibility and LOI values but lower grain-size indicated the climate was more humid than at present. However, from 1800 to 1100 cal. aBP (Zone III; 42–27 cm), lower concentration of total pollen, aquatic plants, shrub and herb, arboreal pollen, and amounts of aquatic plants, Polypodiaceae spores and typical Phragmites fan-shaped phytolith than those in Zone II, and the lowest value of LOI and susceptibility suggested a dry climate. Compared with Zone III, Phragmites fan-shaped phytolith as the implication of a warm and humid climate increased again in Zone IV (27–15 cm; 1100–600 cal. aBP). Percentages of shrub and herb decreased, while those of arboreal pollen composed by Betula and Picea increased greatly with a peak value of 27%, implying a high plant diversity and biomass with abundant aquatic plants. But since cal. 600 aBP (Zone V; 15–0 cm), concentration of total pollen, aquatic plants, shrub and herb, and arboreal pollen decreased again to their minimal values in the peat layers. However, pollen percentages of shrub and herb increased compared with Zone IV, while those of arboreal pollen decreased rapidly, reflecting a drier climate.