The paddy soil is an anthropie soil. Under long term rotation of rice and upland crops, a compact solum with abundent capillary pores and marked vertical joints is formed. In submerging season the water percolates downward unevenly, the larger pores are filbed with water, whereas the closed pores are still occupied by air. Part of iron and manganese come from the plowed horizon are oaized and illuviated irn solum, and some illuviated iron and manganese in solum may be reduced again by the soluble organic matter, and greyish coating and gleyed spots are formed on the surface of larger pores or cracks. Together with the rusty streaks, the gleyed spots and Fe-Mn mottlings form the unique mined mottled or spotted solum of the soils.In order to study the characteristics of the mottled solum, soil samples with gleyed spots and rusty mottlings were callected from different types of paddy soil and various. genetic horizons of the soils respectively. Analytical data of various forms of iron and manganese showed that there was a remarkable difference in content of iron and manganese not only among different types of paddy soil, but also among different genetic horizons of a paddy soil. From the distribution of different contents of free and total Fe-Mn in soil, it can be found that where there is high content of Fe and Mn is just the place of ilhuviation of Fe and Mn, while the site of low content of Fe and bin is the locality of the eluviation of Fe and Mn. The illuviation and eluviation of iron and manganese in paddy soils are very complex, which, are closely related to water regime of the soil. Generally speaking, under the influence of percolating water, eluviation and illuviation are alternatively and frequently occurred in the plowpan, percolating horison and aide bleaching horizon, which results in a well developed spotted layer with gleyed spots and Fe-Mn mo ttlings, while in stagnating horizon such layer is weakly developed.