The soil cover of Osa river basin is described in the article, its variety caused by features of a geological structure, relief, climate, vegetation and anthropogenous impact is revealed. Set of factors of soil formation which gives prerequisites for forming of special types of the soils which aren’t fitting into traditional representations of zone types of a taiga and forest zone – chernozems, dark-humic and other soils under steppe vegetation is studied. In total three trunks, nine departments, 27 types and 46 subtypes of soils are allocated. It is established that the main area (more than 7 0 %) is provided by the soils entering into departments of the accumulative and humic, organo-accumulative and textural differentiated soils, agrozyom, and the insignificant territories are busy with full-height types of soils of structural and metamorphic department, litozyom, abrazyom, alluvial. 37,3 % of the general territory of a research occupy agricultural holdings, from them about 12,8 % are used now, 87,2 % are in abandon condition. The map «Soils of Osa River Basin» is provided in the article.