Abstract: “Probiotics ferment” was applied to treat piggery wastewater, the results showed that the chemical oxygen demand (COD) decreased by 66.7%, five-day biochemical oxygen demand (BOD) decreased by 65.9%, suspended substances declined by 93.5%, ammonium nitrogen and total phosphorus decreased by 70.4% and 42.9% respectively. After treatment, the indexes of COD and BOD in piggery effluent reached the standard of irrigation water quality.