The invention discloses a large-scale piggery dung treatment ecological circulation system which comprises a dung collection unit, a solid-liquid separation unit, an anaerobic fermentation unit, a biogas utilization unit and a biogas slurry utilization unit. The dung collection unit comprises a slurry collection tank, a dung accumulation tank, a settling tank and a slurry storage tank, the solid-liquid separation unit comprises a solid-liquid separator and an organic fertilizer treatment device, the anaerobic fermentation unit is a multistage anaerobic reaction device and comprises a primary anaerobic reaction tank and a secondary anaerobic reaction tank, the biogas utilization unit comprises a biogas cabinet, a biogas purification device and a biogas power generation device, the biogas slurry utilization unit comprises a biogas slurry storage tank, a forestry irrigation device and a farmland irrigation device, and high-temperature oxidation resistant plastic soft protection layers are arranged above the dung accumulation tank and the slurry storage tank. Dung water is fermented to generate biogas and biogas slurry, organic fertilizers are generated after solid-liquid separation, the possibility of secondary pollution caused by waste gas is avoided, waste is effectively and sufficiently reused, and comprehensive utilization rate is increased.