Taking the communities of the sample sites in Aershan of Inner Mongolia as an investigation object,the indices affecting plant diversity were studied.The investigation was carried out in three different forest types(natural forests,plantations and regenerated forests after fire).Results show that 95 plant species belonging to 19 families and 50 genera were identified in total.Of these species,nine were arbors,six were shrubs and the other 80 were herbs.We found some differences in the dominant species of different layers in three forest types.Natural forests had the largest importance value for the total number of species,followed by plantations and regenerated forests after fire.Plantations and natural forests had a similar change in richness indices.The largest value of richness indices was obtained in natural forests,while the lowest value was in regenerated forests after fire.Three diversity indices(Simpson’s,Shannon-Wiener and Pielou’s indices) indicate a similar trend in all sample plots.With an increase in elevation,values of diversity indices first increased and then decreased.In different forest types,similarity between natural forests was largest,while similarity between the regenerated forests and plantations was lowest. Taking the communities of the sample sites in Aershan of Inner Mongolia as an investigation object, the indices affecting plant diversity were studied. The investigation was carried out in three different forest types (natural forests, plantations and regenerated forests after fire). Results show that that 95 plant species belonging to 19 families and 50 genera were identified in total. Of these species, nine were arbors, six were shrubs and the other 80 were herbs. We found some differences in the dominant species of different layers in three forest types. Natural forests had the largest importance value for the total number of species, followed by plantations and regenerated forests after fire. Plantations and natural forests had a similar change in richness indices. The largest value of richness indices was obtained in natural forests, while the lowest value was in regenerated forests after fire.Three diversity indices (Simpson’s, Shannon-Wiener and Pielou’s indices) indicate a similar trend in all samp le plots.With an increase in elevation, values ​​of diversity indices first increased and then.In less forest types, similarity between the natural forests was largest, while similarity between the regenerated forests and plantations was lowest.