Abstract: A pilot-scale sequential batch reactor (SBR) was built in the duck farm, the duck farm biogas slurry was diluted as the influent, and the influent COD was regulated with sucrose, to evaluate the efficiency of nitrogen and carbon removal and the microbial community succession in the process of SBR treating the biogas slurry of the duck farm. The results showed that Stage Ⅰ (1-20 d) was the sludge inoculation and water quality adaptation stage, in which the influent C/N was controlled to be less than 2, and the concentrations of COD and NH₄ ⁺-N were around 200 mg/L. It was found that the removal efficiencies of COD and NH₄ ⁺-N rapidly increased to 80% and 90%, respectively, within the first 8th day. Stage Ⅱ (21-55 d) was the stabilization stage, in which C/N of the influent was also less than 2, and the concentrations of COD and NH₄ ⁺-N were 200-500 and 200-400 mg/L, respectively. In this stage, the removal efficiencies of COD were fluctuated around 60%, while the removal efficiencies of NH₄ ⁺-N were more than 80%. Stage Ⅲ (56-95 d) was the simulation stage for organic concentration change, in which C/N of the influent was in the range of 1.2 to 5.5, while the influent COD and NH₄ ⁺-N concentrations were 300-1 400 and 150-400 mg/L, respectively, and the removal rate of COD and NH₄ ⁺-N was greater than 80% in this stage. Meanwhile, low temperature was one of the main limiting factors for SBR nitrogen and carbon removal. Full-length sequencing of 16S rRNA from microorganisms revealed that Proteobacteria and Gammaproteobacteria were the dominant microbial flora at the phylum and class levels in the system, respectively. A significant shift of microbial community in terms of genus level was detected. The dominant microbial community species with nitrogen and carbon removal functions were formed after the operation stabilization. In general, SBR could achieve efficient nitrogen and carbon removal and had promising application potential in the real practice of treating biogas slurry from duck farm with a characteristics of high COD concentration and low C/N.