【Objective】In order to reveal the response mechanism of microbial community and ecological network to straw returning process in typical fluvo-aquic soil, we experimented with different straw-returning treatments under long-term wheat-maize rotation.【Method】The high-throughput sequencing and ecological network methods were utilized to analyze the soil bacterial community composition, bacterial network co-occurrence and their relationships with soil nutrient concentrations.【Result】The results indicated that compared to straw removal and no nitrogen fertilizer treatment, straw returning with conventional fertilization treatments significantly reduced soil pH, while increasing the content of TN, SOC, AP, AK and NO₃^--N(P < 0.05). The treatments of straw burying with nitrogen fertilizers were beneficial for increasing soil nutrient content. Moreover, no significant difference in bacterial alpha diversity was observed between different straw-returning methods and different amounts of nitrogen fertilizers, but a significant difference was observed in bacterial community structure. Factors such as pH, SOC, and TN drove variations in bacterial community structure.Also, Acidobacteriota, Proteobacteria, Bacteroidota and Chloroflexi were the dominant phyla in the fluvo-aquic soil. Furthermore, co-occurrence network analysis revealed four main ecological clusters that were significantly correlated with soil nutrients. The abundances of taxa in module 1 were found to be inversely correlated with SOC, TN, TP, NO₃^--N, AP and AK(P < 0.001), and positively correlated with pH(P < 0.001). Conversely, the abundances of taxa in module 2 and module 3 were significantly positively correlated with most nutrient content, and negatively related to pH.【Conclusion】Therefore, it can be concluded that straw burying combined with nitrogen fertilizers can improve soil nutrient by regulating ecological relationships of microorganisms. The findings of this study can provide a scientific basis for the efficient utilization of straw and the efficient management of soil fertilization.