In the forming process of paddy soil derived from red earth,transformation and movement of matter are proceeded under the conddtions of oxidation-reduction and periodical alternation of drying and wetting in which the submerging reduction is dominant.The condition not only promote the accumulation of organic matter,but also the ratios of E.H./T.H.and H.A./F.A..The reaccumulation of bases can make the acid and base-unsaturated red earth develop info paddy soil derived from red earth with very high degree of base saturation.The eluviation process induced by oxidation-reduction and compleaation result in redistribution of chemical elements in solum and alleviate the allitic process of red earth,which are favorable for maturation and Fertility promotion of paddy soil.The soil physical properties and characters of soil profiles are also changed due to the conditions mentioned above.The pcrcosubmergic horizon with cloddy structure,coatings and the obvious illuviation of Fe and Mg is formed.Soil structure and fertility are improved.The changes mentioned above are positively related to the years of planting rice.The forming process of paddy soil derived from red earth could be divided into two stages,i.e.the stage of embryonic pattern due to submerged condition and the stage of transitional pattern due to perco-genetic process.The perco-genetic paddy soil with basic characteristics of paddy soil can be formed preliminaryly in ten years.