After a review of the study on soil fertility at home and abroad and of our recent it is clearly reeongnized that in studying soil fertility,both the basic materials affecting the fertility and the patterns of pedon structure of soils should be investigated in a comprehensive way.In black soil,the organo-mineral eompLeaes with different binding status are the basic substances influencing soil fertility.The quantitative variation of various groups of organo-mineral complexes induces a series of changes of nutrients and moisture in soil.In fertile black soil,the total amount of the microaggregates <10μm is above 50%.They are the main parts influencing fertility.The humification and transformation of organic matter are regulated by the soil enzymes.Their activity can reflect the nutrient status and physico-chemical praperties of soil to a great extent.In fertile black soil,humus,humin and humie acid combined with calcium are distributed uniformly in the whole soil mass.It helps improve the formation and uniform distribution of stable structure in soil.