Thy fertility status of three paddy soils (permeable paddy soil,paddy soil and that on meadow soil) were studied.Compared with the results of upland milar origin the following differences were observed.1.Condensation of humus was weaker.2.Amount of different fractions of microaggregates<10 μm were dereased.3.Contents Of C,N,P,were moderately decreased from fine to coarse fractions of microaggregates.4.Adsorption and desorption of P and NH⁴⁺ by microaggregates were stronger.5.Water retention capacity was higher and water permeability was lower.It has been proved that the different fractions of microaggregates<10μm in both paddy soils and upland soil developed from organic soil contained more humus are the main parts influening fertility,while the different fractions of microaggregates>10 μm in both paddy soils and upland soils developed from brown earth containing less humus are the main parts influening fertility.