According to systematic research on the phytolith fossils in the sediment of core AC2 from the Caohu Lake, three phytoliths zones were divided. Based on changes in the main components in the phytolith zones and principal components analysis, the evolution of paleoenvironment and paleoclimate in the past 300 years was reconstructed. There are two warm periods（1770 s—1780 s；1890 s—1970 s ）, one cold period（1780 s—1890 s）and one warming stage（1970 s—2003）in the last 300 years. The environment changes of each period in the Caohu lake area were further discussed, compared with the climate changes of the historical documents and instrumental data of Hefei and the mid-lower reaches of the Yangtze River.