Stability is an indicator of forest community structure and function and has been a focus of ecological research. Four typical forest communities (Ilex purpurea and Pinus elliottii mixed forest, Quercus and P. elliottii mixed forest, P. elliottii forest, and Schima superba forest) in Jiangsu Province, East China were used. Fourteen factors were chosen as the parameters to build an evaluation model that aimed to evaluate the stability of the four selected communities using the mathematical ecology method. The results showed that the diversity could not fully represent the stability. Forest density variety mainly causes the differences in stability among the forest communities. Stability of P. elliottii forest > I. purpurea and P. elliottii mixed forest > Q. and P. elliottii mixed forest > S. superba forest. P. elliottii forest may become conifer-broadleaved mixed forest. S. superba forest may become Q. and S. superb mixed forest due to the limited growing space. Two types of conifer-broadleaved mixed forest may be developing to the deciduous broad-leaved or evergreen broad-leaved mixed forest in the future. The density of S.superba forest was too greater to be etable; thus, appropriate efforts should be made to enhance the stability in forest communities.