Abstract: In this study, we sampled roadside plant communities inside and outside the Lushan Nature Reserve, Jiangxi Province, in order to compare the richness and floral origin of alien plant species. A total of 21 alien plants were observed in the plots, with half of them belonging to cosmopolitan genera. There were more alien plants of temperate origin in the montane area (inside the reserve) than those in the plain area (outside the reserve). The two regions had a significant difference in the composition of native and alien plants in the roadside communities. Eleven alien species occurred both inside and outside the nature reserve; among them, only Erigeron annuus, Ambrosia artemisiifolia and Bidens frondosa differed significantly in occurrence between two regions, suggesting that the roads may act as a pathway for invasion of some alien plants. Complex topography and altitudinal gradients make Lushan Nature Reserve harbor more alien species and traffic corridors may facilitate the spread of some invasive plants, especially for the species outside the nature reserve.