[Aim] In recent years, the taxon and number of alien invasive plants have increased in Inner Mongolia, resulting in serious harm to local organisms and the environment. However, related research is lacking. Understanding the species composition of alien invasive plants and analyzing their life forms, origins, and introduction routes can provide basic data for the management and prevention of alien invasive plants in Inner Mongolia. [Method] Based on field investigations, literature, and database collection, alien invasive plants in Inner Mongolia were classified and analyzed using the above mentioned basic data. [Result] A total of 94 alien invasive species were recorded in Inner Mongolia, which belonging to 65 genera and 24 families. Among which, the families of Asteraceae, Amaranthaceae, and Gramineae contained more than 10 species, accounting for 23.4%, 11.7%, and 11.7% of the total species, respectively. Life form analysis indicated that annual, biennial, and perennial herbs accounted for 72.3%, 26.6%, and 19.1% of the total species, respectively, whereas few trees and shrubs were found. In Inner Mongolia, most of the invasive alien plants originated from North America (44 species, 46.8%), and the least originated from Africa (8 species, 8.5%). Regarding the introduction route, intentional and unintentional introduction accounted for 48.9% and 51.1% of the total species, respectively. [Conclusion] Many alien invasive plants were found in Inner Mongolia, covering a wide range of families, among which Asteraceae, Amaranthaceae, and Gramineae dominated. Their sources were wide, and unintentional introduction was increasing. To prevent harm to local ecology, economy, and human and animal health, it is important to ensure risk assessment and effective control over time.