The process of recycling anaerobic effluent as cooking water for citric acid fermentation was studied,which included the effect of ammonia nitrogen on citric acid fermentation and related pretreatment.The results showed that ammonia nitrogen in the anaerobic effluent caused the excess of nitrogen source of medium,which reduced the citric acid yield.The inhibition was reduced after ammonia nitrogen removal by air stripping treatment and then was basically eliminated after solid content removal by coagulation treatment.Finally,the citric acid yield of treated sample was 17.3% higher than that of untreated sample and 2.8% less than that of deionized water sample,which reached the normal level.The recycling process reduced pollution and saved water resource,so it should possess some application potential.