Abstract: Zigui County is a key area of biodiversity in the Yangtze River Basin and an important ecological barrier in the Three Gorges Reservoir area. Based on the field investigation of the species composition, distribution of harmful alien invasive plants, the risk assessment system of alien invasive plants was constructed. The analytic hierarchy process ( AHP ) according to the risk, current situation, harm and management difficulty was adopted in this study. The results showed that: ( 1 ) There were 68 species of alien invasive plants in Zigui County, belonging to 22 families and 45 genera. The species of Asteraceae, Amaranthaceae, Euphorbiaceae, Poaceae, Plantaginaceae and Fabaceae were the main families. The number of Asteraceae plants was up to 17 species, accounting for 25 % of the total species. ( 2 ) The number of invasive plant species was the largest in the range of 150-300 m above sea level, and they showed a downward trend with the increase of altitude. Maoping Town ( 51 species ) was a high outbreak area of invasive plants in various towns.( 3 ) The risk assessment of 68 alien invasive plants showed that the risk levels of Erigeron canadensis, Erigeron sumatrensis, Alternanthera philoxeroides, Erigeron annuus, Bidens pilosa and Symphyotrichum subulatum were high. It is suggested to strengthen the prevention and control of the spread of high-risk invasive plants such as Erigeron canadensis. A dynamic monitoring of the potential hazards of low-risk invasive plants was essential, to provide scientific basis for the management of alien invasive plants in Zigui County.