Abstract: 【Objective】 The objective of this study is to evaluate the effects of different ratios of defect fragrant pear juice residue supplementation on fermentation quality and nutrient composition of alfalfa silage.【Methods】Mixed alfalfa silage was prepared with 10%, 20% and 30% concentrations of defect fragrant pear juice residue, after anaerobic fermentation 30 d, silage samples went through analysis.【Result】The results showed that 10% or 20% of defect fragrant pear juice residue supplementation reduced the pH value and CP content, which were much lower than those of the control group of silage (P < 0.05); The content of lactic acid was significantly higher than that of the control group(P<0.05). The fermentation quality of silage was significantly improved by adding defect fragrant pear juice residue.【Conclusion】10% and 20%of defect fragrant pear juice residue is good for improvement of alfalfa silage quality.