Abstract: Fertilizer use efficiency is declining in the pursuit of higher yields due to increasing farm chemical fertilizer inputs, farmland soil hardening, soil available nutrients losing, and soil acidification. To explore the effects of integrated optimized fertilization on soil nutrients and crop yield in rapeseed-rice multi-cropping field in the middle reaches of the Yangtze River, a five-year field experiment with three fertilization treatments, which were conventional fertilization (CK), nitrogen reduction fertilization (KF), and integrated optimized fertilization (BMP) treatments, was conducted. Soil organic carbon, nitrogen, phosphorus, and potassium contents and crop yield of a rapeseed-rice multi-cropping system were investigated, and the relationships between soil ecological stoichiometry and crop yields were explored. Compared to the CK treatment, soil organic carbon, total nitrogen, and total phosphorus contents under BMP treatment increased by 5.77%–16.81%, 1.73%–6.36% (except for 2019), and 6.84%–19.44%, respectively, from 2018 to 2022. The soil C∶N ranged from 10.12 to 22.21, C∶P ranged from 12.47 to 22.45, and N∶P ranged from 1.01 to 1.39 under different treatments. Compared with CK treatment, soil C∶N under BMP treatment increased, while soil N∶P decreased; soil C∶N (except for 2021) and N∶P (except for 2018 and 2022) under KF treatment decreased. C∶N under BMP treatment was the highest, and the difference of C∶N between BMP and CK treatments was decreased over time. Compared with the CK treatment, the rapeseed yield under the BMP treatment increased by 4.49%–26.78% and the rapeseed yield under the BMP treatment showed increasing trend as the straw returning duration increased, while that under the CK and KF treatments decreased first and then increased. Rice yield under the CK and BMP treatments showed increasing trend from 2018 to 2022, whereas rice yield under the KF treatment decreased slightly from 2020 to 2021. The marginal yields of N, P, and K in rapeseed and rice increased with time, and the increase of marginal yields of rapeseed was higher than that of rice. Correlation analysis revealed that the yield of rapeseed and rice was significant positively correlated with soil total nitrogen and total phosphorus contents (P<0.05 or P<0.01), most of the soil nutrients and stoichiometric characteristics were significantly correlated, and the average annual temperature was significantly correlated with soil nutrients and stoichiometric characteristics. In this study, long-term positioning monitoring was adopted to explore dynamic changes in soil nutrients through a combination of organic and amount-reduced fertilization. In summary, after the organic and inorganic fertilizers are applied to the field, the fertilizer reserving, supplying capacities and buffering power of soil are enhanced, the nutrients required for crop growth are continuously met, which improves the soil structure and increases the crop yield. Therefore, the results of this study indicate that the integrated optimized fertilization is the best fertilization mode for optimizing regional farmland nutrient management.