The composition and structure of five natural secondary forests in Shenzhen were studied based on data of plots and were compared with Hong Kong zonal forest, so as to detect their succession stage and species diversity level. According to succession process of subtropical forest and ecological characteristics of dominant species, the authors speculate that five communities are at different stages. Sinosideroxylon community dominated by heliophilous evergreen broad-leaved tree (Sinosideroxylon wightianum) and conifer tree (Pinus massoniana) is at the third stage. Itea + Acronychia community dominated by two evergreen broad-leaved heliophytes (Itea chinensis and Acronychia pedunculata) is at the fourth stage. The others, I.e., Schefflera, Sterculia and Cleistocalyx + Sterculia community are at the fifth stage where some mesophytes are dominant but heliophytes have a weighed percentage of importance value. Due to succession stage and different forest management and conservation models, the species diversity of five communities is significantly lower than that of Endospermum community in Hong Kong. The values of Shannon-Wiener index and Pielous evenness index of five communities are 2.04-2.953 and 64.2%-74% respectively, but those of the Endospermum community are 4.74 and 79% respectively. The current situation of these communities suggests that the necessary measures should be taken to protect and restore the communities.