Abstract: In order to prepare mutton waste liquid fertilizer,mutton waste was used as a raw material, based on Bacillus subtilis,Bacillus cereus,Penicillium citreonigrum,and Aspergillus oryzae,to the fermentation experiments of single and mixed strains,and the best combination of the fermentation process conditions were optimized,the free amino acid nitrogen content in the fermentation product as an indicator to evaluate the mutton waste liquid fertilizer. The mixed mutton mixture was used to decompose part of the mutton. The optimum fermentation conditions were temperature 30 ℃,pH6.0,inoculation volume 10%,and rotation speed 160 r/min. Under this optimal condition,the total nitrogen content was 37.16 mg/mL provides some guidance for the comprehensive utilization and development of animal by-products.