Abstract: In order to explore the effect of cultivated tree species on the local plant species diversity, an investigation was conducted by the typical sampling method in three typical plantations (Phyllostachys heterocycla artificial forest, Metasequoia glyptostroboides artificial forest and Cinnamomum camphora artificial forest) in the Laobanshan mountain, Ya'an city, Sichuan province. Based on the community survey, the species composition,importance value and species diversity indexes were calculated.The results indicated that:(1) A total of 94 species were found in P.heterocycla artificial forest, belonging to 78 genera and 59 families, a total of 82 species were found in M.glyptostroboides artificial forest,belonging to 67 genera and 46 families,and a total of 80 species were found in C.camphora artificial forest, belonging to 70 genera and 47 families.The species diversities of P.heterocycla artificial forest were higher than other forests.(2) By analyzing the important values, it was discovered that bamboo plants, M.glyptostroboides and C.camphora were evidently dominant in upper layer of the plantations; Cryptomeria fortunei and Cunninghamia lanceolata were found in the shrub layer of P.heterocycla and C.camphora artificial forest; C.camphora seedlings showed that C.camphora artificial forest achieved natural regeneration, but M.glyptostroboides artificial forest could hardly regenerate;Commelina communis and Achyranthes aspera were in the dominant position in three artificial forests herbs. (3) Different artificial forests species richness showed shrub layer > herb layer > tree layer, D, H, H' and J_SW of tree layers were less than those of other layers,H' of shrub layer and herb layer was greater, and the J_SW was relatively small in M.glyptostroboide and C.camphora artificial forest, and the artificial forests community development were not stable. (4) The stand improvement of three artificial forests should be conducted.