In the present study, changes in soil physical, chemical and biological properties in paddy fields of a cultivation chronosequence were observed by field sampling in a typical red soil region in subtropical China, Jiangxi Province.After cultivation, clay (< 0.002 mm) content decreased from 39% of the orig-i nal uncultivated wasteland to 17% of the 80 a paddy field, while silt (0.02~0.002 mm) content increased.Soil pH increased generally by 0.5~1 units, the 0~10 cm soil organic C and total N contents increased respectively from 4.58 g kg^-1 and 0.39 g kg^-1 of the original to 19.6 g kg^-1 and 1.62 g kg^-1 of the 30 a paddy field, and then remained stable.With 3 a cultivation for paddy field, total P content increased from 0.5 g kg^-1 to 1.3 g kg^-1, which suggested that fertilizer application can accelerate phosphorous accumulation in paddy field.0~10 cm soil total K content showed a decrease by 80% with a 80 a cult ivation.Total Fe and free Fe contents also showed a decreasing tendency.Bacterial population in-creased and urease activity intensified obviously.In this chronosequence it appeared that it took 30 year to raise fertility to a relatively constant value, seen after 80 a cultivation.