Abstract: Based on the investigation data of main forest community in Sheshan National Forest Park of Shanghai, the main community types, the plant species diversity of forest communities and their succession were calculated and analyzed by measuring the community similarity and species diversity. The results showed that there were 7 types of forest community, Quercus albus forest, Phyllostachys edulis stand, Cinnamomum camphora forest, Celtis sinensis-Zelkova schneideriana mixed forest, Celtis sinensis-Robinia pseudoacacia mixed forest, Firmiana forest and Liquidambar formosana-Robinia pseudoacacia mixed forest, in Sheshan National Forest Park of Shanghai. The plant diversity of all the 7 types of forest community above mentioned was poorer than that in the neighbor area of Zhejiang Province. The deciduous species, such as Ulmaceae, Quercus, were the dominant tree species, while the evergreen tree species, such as Cinnamomum camphora, Phyllostachys edulis, Castanopsis sclerophylla and Ligustrum lucidum, were little in tree species composition. From the view point of forest succession trend, 3 types of forest, Quercus albus-dominated zonal forest, Phyllostachys edulis stand and evergreen-deciduous mixed forest of Lauraceae, Ulmaceae and Oleaceae plants, would be developed in Sheshan area in the future.