Micromorphological characteristics of the scnls under simulation of intensive cropping system for four years were investigated by means of the thin section and scanning electron macrostopic techniques. The micromorphological observation showed that porosity of clayey soil increased with the organic materials applied in soil, in the soil applying organic material, not only the rnacropores occured among the aggregates, but the medium and micropores also exsisted in the aggregates, which formed a network of pathways beneficial for the movement of both air and water in soil. This structure in soil, consequently, is also favorable for the field cultivation and sowing of upland crops after harvesting rice crop in intensive farming system.Directly applying rice straw in soil promoted soil aggregation and increased soil porosity. Under treatment of directly applying rice straw,iron coatings were formed on the wall of soil pores, which stabilizes the network of pathways in soil. Due to tight arrangement and formation of massive structure resulted from puddling, few soil pores and no iron coating on the wall of pores were observed in the thin section of the soil. Iron streaks, however,was found in the soil matrix. The morphology of soil. structure varied with different flooding duration of soil. It is indicaxed that the flooding condition of soil under double.cropping rice is a factor to result in the cotnpactian and lack of pores in soils.