Accurately assessing changes in soil total nitrogen content (STN) in farmland soil is the basis for effective field management. In this study, an area of 2.32 M hm² of paddy soils, or 37 counties (or cities) of in the Tai-Lake Region, was delineated as study zone. The 1:50 000 high accuracy paddy soil database developed and based on the analysis of the 1 096 samples of topsoil collected during the Second National Soil Survey in 1982 and the 1 393 samples of topsoil collected during the “973” Project in 2000 in this region was used as the basis for quantifying dynamic changes in STN in the paddy soils of the region over the past 20 years. Results show that STN in the paddy soils increased by 0.21 g•kg^-1 in the period from 1982 to 2000, displaying a significant accumulating trend, especially in degleyfied paddy soil, in which STN increased the most significantly or by as high as 17.0%. But in gleyfied paddy soils, it decreased by 26.2%. The dynamics of STN also varied with landform. In the low mound and hill areas it increased significantly or by 31.8%, while in the Tai-Lake plain region and polders it increased slowly up or by only 9.8%. Moreover, the dynamics of STN varied, too, with administrative zone, the mean STN of Anji, Changxing, Chuansha, Minhang, Yuhang and Chongming increased by more than 40%; while that of Wu, Qingpu, Jiashan and Danyang decreased somewhat. It is quite clear that as a whole, the soil total nitrogen in paddy soil of the Tai-Lake Region varied sharply with area, so it is imperative to reduce field fertilization, case-specifically in the light of soil subgroups, sub-regions and regional nitrogen enrichment degree so as to prevent soil nitrogen loss and water eutrophication.