Abstract: At present, most of the biogas engineering biogas slurry production is large, the export is not smooth production is the biggest problem in the industry. The anaerobic fermentation gas production experiment was carried out with chicken manure and cow manure as fermentation raw materials and biogas slurry as inoculant to demonstrate the effect of biogas slurry reflux on the gas production performance of anaerobic fermentation. The experimental results showed that the biogas production of A₂ mixed with cow manure was not inhibited due to biogas reflux during the anaerobic fermentation cycle, and the methane concentration and daily gas output of A₂ were generally higher, the methane concentration and daily gas output of A₂ were 25.3% and 60.6% higher than that of A₁ group. In group A₁, reaction rate lag, high concentration of NH₄-N, accumulation of organic acid and low concentration of methane inhibited gas production.