Leymus chinensis alliance, one of the most widely distributed communities in China’s temperate steppe, is a grassland vegetation type with the highest utilization value for animal husbandry. Investigating the distribution and community characteristics of Leymus chinensis formations can provide data for the management and restoration of natural grasslands. In this study, we investigated the characteristics of L. chinensis communities of 46 sites in Nei Mongol, including species composition, ecological characteristics, and community classification of L. chinensis alliance. A total of 187 vascular species, belonging to 109 genera and 37 families, were recorded. Asteraceae was the family with the most species, while Artemisia was the genus with the most species. Perennial herbs were the dominant life form, accounting for 71.66% of the total species. Xerophyte dominated the communities, accounting for 67.38% of the total species. The geographic composition of the system was dominated by the Eastern Palearctic species, followed by the Central Asian species. The L. chinensis alliance could be divided into 8 association groups, including Leymus chinensis - tussock, Leymus chinensis - semi-shrubby, Leymus chinensis - rhizome, Leymus chinensis - Carex, Leymus chinensis - annual/biennial, Shrub - Leymus chinensis, Leymus chinensis - bulbiferous herb and Leymus chinensis - forb and 26 associations.