Species composition and vegetation distribution patterns of Lake Caizi were investigated during September 2005 to October 2009.Combining with the data of neariy ten years monitoring, the succession of macrophyte communities and its driving factors were analyzed in Lake Caizi.There are 147 vascular plant species belonging to 101 genera in 42 families.The vegetation distribution pattern exhibited the following characteristics;1) the dominant associations of submerged plant communities(Potamogeton malaianus and Hydrilla verticillata) and floating plant communities(Trapa bispinosa) in the central areas of lake with deeper water level;2) the dominant associations of emergent plant communities (Zizania caduciflora and Polygonum orientale+P.lapathifolium) and floating plant communities (Nymphoides peltata) near the shore areas with shallow level;and 3) the dominant associations of wetland plant communities(Ranunculus polii, Carex thunbergii and Potentiua supina) on the lake beach in spring.The patchy area of Phaldris arundinacea distributed on the beach, and the communities succession exhibited the following series:1) submerged plant communitie stage with the dominant associations of Vallisineria natans+Hydrilla verticillata;2) floating plant communitie stage, T.bispinosa+N.peltatum;3) the stage of several submerged plant communities, P.malaianus;4) the transition stage from macrophjrte-dominated to phytoplankton-dominated.The distribution area of P.arundinacea had expanded in the past 5 years.The driving force of succession was human factors as aquaculture, reclaim-ation, as well as hydrological changes, etc.