In this paper, soil cartography is considered to study and express the forms of structure of soil mantle distribution in space. The principle that soil mapping should be based on the genesis of soil combination and the miethod-that attention should be paid on both simple de lineation and compound delineation that can promote the quantified degree have been sugge sted. It also deals with the components of soil mapping units, the bases of their determination, the corresponding categories of soil classification, and the grades and arrangement o soil mapping unit system, as well as the relationship and differeces between soil mapping unit and soil classfication unit. Having generalized the structural forms of both simple and compound delineations and their forming. factors, ideas of classification and examples are formu fated first on division of the compound delineations into forming fartor suquences such a those of relief, parent material, historical evolution,, and cultivation, and then on subdivision into numerous types under each of the above forming factor sequences according to the genetic relations amoung the components of soil combination as shown by the combination of delineatians, the regularity of geographic distribution of the soils in China has been discussed.in addition, the significance of mapping generalization in the soil mapping on small scales, the ways of generalization, points for attention, and the prospects for the small scale sail mapping have also been discussed.