【Objective】Though carbon sequenstration of agricultural soils is one of the focuses of current concern, little has been reported on how soil carbon and nitrogen varies dynamically in Hydragric Anthrosols different in water regime and cultivation age. 【Method】Taking advantage of the long-term paddy cultivation history in China, four types of Hydragric Anthrosols along the chronosequence from a dozen years to a thousand years, were specified in Jinxian of Jiangxi (Jinxian sequence), Cixi of Zhejiang (Cixi sequence), Zhongshan of Guangdong (Zhongshan sequence) and Baoying of Jiangsu (Baoying sequence) for exploration of how organic carbon (SOC) and total N (TN) in the soils responds to changes in water regime and cultivation history. 【Result】Soil organic carbon accumulation was mainly affected by water regime and content of soil organic carbon. For the Jinxian sequence (surface water type), soil organic carbon accumulated mainly in the anthrostagnic epipedon within the first 100 years of rice cultivation and then in subsoil with cultivation going on. For the Cixi sequence (well-drained water type), soil organic carbon accumulated only in the anthrostagnic epipedon and reached to the point of saturation within the first 50 years of rice cultivation. For the Zhongshan sequence (ground water & well-drained type), soil organic carbon reached to the point of saturation within the first 30 years of rice cultivation and then slightly decreased in content with cultivation going on as the groundwater table lowered. In contrast, for the Baoying sequence (also ground water & well-drained type), soil organic carbon was relatively stable in content within the first 5 years of rice cultivation and then significantly decreased with the groundwater table within the following 15 years. All the four types of Hydragric Anthrosols tended to be similar in carbon/nitrogen ratio in the cultivated horizon with paddy cultivation going on for long and had similar carbon-nitrogen coupling balance in highly mellowed plow layers of the Hydragric Anthrosols. The paddy soils of the Jinxian sequence could be deemed as a stable organic carbon sink within 300 years though their carbon sequestration rates tended to be low. For instance, SOCD of the soils increased on average by 3 g•m^-2•a^-1 only. Following the current normal management and utilization levels, the paddy soils of the Cixi, Zhongshan and Baoying sequences would have their soil carbon pools saturated up to a level compatible tto their water regimes within 15～50 years, thus keeping SOC in a relatively stable balance. In soils relatively high in ground water table, high yield oriented practices, such as drainage, could lower the ground water table, which could lead to rapid depletion of soil organic carbon. 【Conclusion】Evolution of the soil organic carbon pool in and carbon sequestration capacity of Hydragric Anthrosols are highly subject to the impacts of water regime and initial organic carbon content in the soil. It is, therefore, essential to pay enough attention to adoption of certain high-yield oriented agricultural practices and agricultural policies that may cause changes in water regime and their impacts on the soil organic carbon pool in paddy fields. The Jingxian, Zhongshan and Baoying sequences of Hydragric Anthrosols are basically consistent in evolution characteristics of TN and SOC. Hydragric Anthrosols of the Cixi sequence contain relatively more inorganic N and differ quite sharply from the others in evolution characteristics of TN and SOC. So adequate attention should be paid to evaluation of impacts of excessive accumulation or depletion of N in Hydragric Anthrosols that are high in inorganic N content on long-term rice cultivation.