[Aim] To study the effects of planting exotic tree species, Larix kaempferi and Chamaecyparis pisifera, on the forest communities and species diversity in northwest Hubei Province, a comparative analysis was conducted among four distinct forest communities composed of planted Larix kaempferi, Chamaecyparis pisifera or local tree species. This study aims to provide basis for evaluating the invasion risk of exotic tree species.[Method] A survey was conducted to compare differences among communities of L. kaempferi, C. pisifera, and local tree species, using at least four plots each.[Result] Plant species richness in the sample plot of the L. kaempferi plantation was very high, comparable to that of the local natural forest sample plot. The diversity indices of the understory shrubs and ground vegetation were high, but not significantly different (P<0.05) from that of the local natural forest. No regeneration seedlings of L. kaempferi were found. The average number of species in the sample plots of the C. pisifera plantations was significantly lower (P<0.05) than that Jiuhua Mountain plantation. The four diversity indices of the tree canopy, shrub layer, and ground vegetation were all lower in the C. pisifera plantations than those of the other plantations. Across the three plots, C. pisifera regeneration seedlings were found at a high number of 479 plants·hm^-2.[Conclusion] The introduction and cultivation of L. kaempferi into forest communities will neither decrease the species diversity of the local forest community nor cause any biological invasion risk. However, the introduction and cultivation of C. pisifera may significantly reduce species diversity of the local forest community and pose a certain degree of threat to their stability.