【Objective】 It is still unclear how key soil nitrogen (N) transformed and how the microbes involved in the transformation evolved along a long-term chronosequences of the soil in the coastal polders in Cixi. 【Method】An indoor incubation experiment was carried out using soil samples collected from coastal polders in Cixi with cultivation age varying in the range of 0~1 000 years to determine N mineralization rate (NMR), nitrification intensity (NI) and number of nitrobacteria (NN). 【Result】Results show that soil conductivity (EC) and pH decreased with aging of the soil, while soil organic matter (SOM) and total N (TN) accumulated in the topsoil, and soil properties changed significantly, especially during the first 50 years of cultivation. NMR varied in the sequence of 220~1 000 a > 0~50 a > 60~200 a; NI displayed a general rising trend with the cultivation going on year after year , but NN increased in the first 20 years, and peaked during the years of 20~60 and then turned downwards gradually, Person correlation and aggregated boosted tree (ABT) analyses show that cultivation history of the soil, EC, and SOM concentration were the dominant affecting factors, explaining 45%, 12% and 11% of the variation of NI, respectively, while soil NH₄⁺-N and available P contents were the ones, explaining 86% and 42% of the variation of NMR and NN, respectively. 【Conclusion】 Therefore, it could be concluded that during the course of sustainable agricultural utilization of the coastal polders nitrification intensity and nitrobacteria abundance increases to a certain extent, but they are subject to the joint impact of historical conditions and contemporary environmental factors.