During the 6th excavation of Chuodun site (E120°50'41",N 31°24'07"),22 pieces of prehistoric farming lands were discovered within 300 m²,Each field was surrounded with bands in between,and ditches or water pools (wells) constructed for irrigation,and some pots wearers (belong to Majiabang culture periods) for water transfer from ditch to field were found in these ditches or fields;more.000 fossil rice grains were screened out,and about 10 to 60 thousands rice phytolith (opal) per gram soil were detected in these ancient lands,all facts above are strong proof indicating these small piece of ancient lands were irrigated paddy fields for rice cultivation by ancient human beings settled in this site.The age of these paddy fields were about 5 907 a BP to 6 280 a BP determined by ¹⁴C analysis.It is in Neolithic period and in agreement with Majiabang culture period identified by archaeological method.The small size of each field which only 0.4 m² to 16 m² and various shape etc.morphological characteristics were reflect the very low production capacity at that time.A soil monolith (P-01) was studied and described,results indicated that there were two buried paddy soil profile piled together.One is prehistoric paddy profile with age of 6 280 a BP (Majiabang cultural period) in the layer of 103～200 cm depth and the other was ancient paddy profile with age of 3 320 a BP (about Maqiao cultural periods to Early Shang dynasty period) in the layer of 42～103 cm depth.It proved that there were several times of flooding or sea water invade resulting to break off agricultural civilization.Another monolith (P-03) only 15 m apart from the above monolith (P-01),but it was not found the prehistoric paddy profile in the layer of 103～200 cm depth indicating early human beings settled in Chuodun site during that periods had no capacity to use hill land for rice planting yet,because of P-03 monolith was located at the foot of Chuodun hills,they had no technology to level it to construct terrace for rice planting,while the same buried paddy profile in the layer of 40～103 cm aged as Maqiao cultural period to Early Shang dynasty period was there same as in P-01.Both buried paddy soils have developed most of the typical characteristics of modern paddy soils.