The transformation of iron oxides in soil in the course of submergence and drainage, and its influence on the soil structure is discussed on the basis of incubation experiment. The yellow brown earth, the red earth and the laterite were added with various amounts of dried milk vetch powder, and incubated under the submerged condition with and without percolation. After 8 months, the incubated samples were dehydrated at various intensity and samples without dehydration were used for check (Table 2). The compleaed iron and amorphous iron oxides contents of incubated samples were influenced obviously by the addition of organic matter, submergence and dehydration, but the influence of dehydrated intensity on the compleaed iron content was insignificant (Table 3, 4&5).