The structural diversity of forests on Baihuashan Mountain, Beijing, was surveyed by a plotless method combined with branch and leaf coverage estimation in the different layers. New structural indices were constructed, calculated and compared among different communities. On the basis of previous work, structural diversity of forest communities at the stand level was described by a vertical complexity index and a horizontal heterogeneity index. From a correlational analysis among the new indices and other commonly used biodiversity indices, we concluded that the new indices are closely related to a tree height inequality index and the Shannon-Wiener index of the tree and shrub layer, which indicated that the new indices were good at indicating structural diversity in the different forests on Baihuashan Mountain. The results show that, in natural forests, structural diversity of pioneer communities is much lower than in late successive communities. In plantations, structural diversity is determined by the stage of development and tree species. Tending would increase horizontal heterogeneity and decrease vertical complexity.