Rice cultivation in China can be dated back 7 000 years ago,it produces about 40% rice grain and occupies 23% of paddy soils worldwide respectively.Rice is one of the staple foods for Chinese.Comparison study on soil quality of prehistoric,ancient and present paddy soils,to reveal the origin,evolution of irrigated paddy fields and paddy soils in biogeochemistry process as well as the mechanisms of sustainability of irrigated rice paddy ecosystem is very important in theory for soil sciences and to promotion food security of our world,this should be one of the priority area for Chinese soil scientists may make great contribution to it.