Accurate assessment of the dynamic evolution process of soil organic carbon (SOC) and total nitrogen (TN) contents and storages holds significant implications for the formulation of efficient farmland soil management policies and comprehension of soil productivity potential. In this study, a millennium soil chronosequence was established based on the paddy soil profiles with reclamation years of 30, 60, 120, 170, 200, 280, 350, 550, 950 and 1 100 years in Cixi City of Zhejiang Province, aiming to explore the evolution and trend of SOC and TN contents and storages in 1 m deep tidal flat soil profiles in this area. The results revealed a decreasing trend of SOC and TN contents with the increase of depth, while exhibiting a fluctuating growth trends with prolonged soil reclamation years, 30 cm and 550 year were the turning points of SOC and TN properties in depth and time, respectively. Approximately 53% and 46% of SOC and TN were stored in the 0-30 cm soil depth, underscoring the significance of sampling depth in SOC and TN retention estimation. Moreover, SOC and TN storages exhibited a linear or exponential growth trend in the millennium formation soil chronosequence, indicating that the reclaimed soil in the study area retains a great potential of sequestration for SOC and TN during our study period. The outcomes of this research offer theoretical underpinnings for the effective management of local soil quality, thereby contributing to the promotion of sustainable agricultural development.