Four group of water-stable microaggregate were separated from calcareous soils by means of three colloidal-dispersing methods.They are the group dispersed by sodium (GI₁),the group dispersed by decalcification (GI₂),the group dispersed by grinding (GII) and the group dispersed by water.The contents of humus,fulvic acid and clay mineral in these four groups showed a tendency as follows:GII>GI₂>GI₁Go.The content of microaggregate<10 μ in four groups is positively correlated with the contents of particles<10 μ,CaCO₃ and in soil.