The complexity of soil’s classifications application of various years for Baikal region soils is noted. Possibilities of soil horizons diagnostics and soil terminology were considered, which are determined by the peculiarities of humus composition, the presence of relict carbonate horizons and predominantly subaerial nature of the mineral substrate of upper horizons of high floodplain soils. The humus horizons of many Baikal region forest’ soils of its properties are occupy intermediate position between AY and AU horizons. For them the index AYu and subrange type name – soddy-darkhumus were proposed. The structure of the soil profiles were examined by the author from stratigraphic positions. It was shown that the soil’s profile carbonates are inherited from before-Holocene cryoarid time. The index for diagnostics of inherited carbonates horizons was proposed. The problems of alluvial soils classification was considered the necessity of accounting of the entire profile structure of alluvial soils, not only the uppermost and youngest part of their profile was notice. The soils of high plains was proposed to refer to the subtype post-alluvial soils.