Abstract: In this study,the quality of Tibetan mutton was evaluated by amino acid and fatty acid quality.Amino acid analyzer and GC( gas chromatography) were applied to analyze the amino acid and fatty acid content.The results demonstrated that the quality evaluation of Tibetan adult meat was superior to Tibetan Lamb meat,AAS( amino acid score) /7.65,CS( Chemical Score) /5.54 and higher content of flavor and function amino acids. The n-3PUFAs / n-6PUFAs value of Tibetan adult meat 11.19% and Tibetan Lamb meat 12.88% were better than the reasonable nutrition value of FAO / WHO( 10% ~ 20%). The content of oleic acid and linoleic acid was higher than others in Tibetan mutton.Tibetan Lamb meat had more type and higher content of PUFA than others. Amino acid and Fatty acid was one of the important factors about measuring the nutrition and grading of Tibetan mutton.