Abstract: The denitrification process in the inclusion zone plays an important role in groundwater nitrate pollution management, where the spatial distribution of denitrifying bacteria is a key factor affecting the denitrification process. Currently, no studies have focused on the effects of soil depth and other physicochemical properties on the composition and structure of denitrifying bacterial populations in the inclusion zone of the Chaobai River floodplain fan area in Beijing. In this study, we used high-throughput sequencing and molecular ecological network technology to study the soil bacterial community in the Chaobai River air inclusion zone profile and analyzed the correlation between environmental factors and denitrification bacteria diversity, denitrifying bacteria structure and composition by Spearman's non-parametric analysis method, redundancy analysis method, random forest analysis method and Mantel Test correlation analysis method. The results showed that the relative abundance of denitrifying bacteria genera showed a certain pattern: nirK>nirS>nosZ. nirS, nirK, and nosZ genes were mainly expressed in nitrogen-fixing bacteria and rhizobia genera, and the OTU association network showed a high proportion of positively correlated edges: nirS-97.47%; nosZ-90.77%; nirK-82.44%. There were differences in LEfSe analysis between the two profiles under the nirS and nosZ genes. pH, ammonia nitrogen content, soil depth, and mucilage content were the main factors affecting denitrification bacteria α diversity; soil depth, redox potential(Eh), soil mucilage content (Clay), and OM were the main drivers affecting denitrifying bacteria community structure. This study initially reveals the differential distribution of denitrifying bacteria in the alluvial floodplain fan of the Chaobai River in response to changes in environmental factors, which is of great reference significance for studying denitrification processes in the air-packing zone