The patterns of solum structure for distinguishing taxa at soil species level consist of basic horizons including surface (ploughing) horizon,and other special horizons,which are naturally differentiated and arranged within the soil profile.For comparative study,the thickness and positron of the basic horizons and speaal horizons in the profile of a depth or 1m.are delimited and defined according to the criteria designed especially for delimitation of the pattern of solum structure.Within a soil genus,the pattern of solum structure is the basis for distinguishing soil species.Under the conditions of soil formation including the integrated influence of natural factors and human activity,the development degree of the diagnostic horizons combined with the differences of soil fertility in surface (ploughing) horizons may serve as the criteria for distinguishing soil species.In this paper,the procedure for classification of soil at the soil species level is discussed.