In accordance with the study’s objective, the article presents the results of systematic and chorological analyses of ferns of the Southwestern Altai in the Kazakhstan Altai mountains, and also analyzes the specificity of the pteridoflora to soil substrates and moisture. The pteridoflora (class Polypodiopsida) was established as consisting of 32 species, belonging to 12 genera and 9 families. In terms of the number of species, the leading families are Woodsiaceae, Dryopteridaceae, Cystopteridaceae, and Athyridaceae, which together account for over 75.0% of the total number of species in the study area. The family-species coefficient of the pteridoflora of the Southwestern Altai at the level of 0.28 indicates a low saturation of families with species and its primeval age. The pteridoflora was found to be associated with five distinct geographical areas. Species with a Holarctic distribution were the most prevalent, comprising 68.75% of the total, suggesting a strong connection to Holarctic floras. According to the growing conditions, ferns are divided into 3 belt-zonal groups: plain-mountain-forest, mountain-forest and high-mountain. The dominant position is occupied by the mountain-forest group – 23 species (71.75%), growing in coniferous, mixed and small-leaved forests, confined to the mountains in the altitude limit of 900-1700 m above sea level. A specificity of pteridoflora to various types of rocky habitats and cliffs was revealed. According to the requirement for moisture supply of ecotopes, ferns are divided into 6 groups, where the dominant position is occupied by the mesophilic ecomorph, represented by mesophytes – 46.8% and mesopetrophytes– 37.5% of the total species composition.