Dianshan Lake, which lies in the border of Jiangsu Province, Zhejiang Province and Shanghai Municipality, is the only freshwater lake in Shanghai Municipality with an area of 62km².It is a shallow and passageway lake, averaging water depth of 2.lm.Species composition, distribution, community type as well as quantitative characters and succession of aquatic vascular plant (AVP) communities in Dianshan Lake during 1991-l992 were studied.The results were summarized as follows: (1) There were 26 species of AVP, belonging to 21 genera and 16 families.Among them, Vallneria asiatica, Poiamogelon criapus, Poiamogeton malaianus and PhraoinUes communis etc.were dominant species.(2) The distribution of aquatic vegetation in this lake exhibited irregular zonations, and might be classified into 3 plant zones (emerged plants, leaf-floating plants and submerged plants) from shore to center of the lake and 12 principal community types.(3) Among the importance values of main species of AVP communities, the maximum was that of V.asiatica and the minimun was those of Najas.The AVP communities were possibly undergoing the change from submerged plants to leaf-Hoating plants, emerged plants or floating plants.(4) The main environmental factors to restrict the growth and distribution of AVP were water depth, transparency of lake water, composition of sediment and artificial disturbance.