Abstract: Based on the degree of hydrolysis,enzymatic hydrolysis conditions of the myofibrillar protein extracted from chicken breast was optimized by response surface methodology in this article,the protein content and amino acid composition of the myofibrillar protein and the molecular weight distribution of the hydrolysates were also measured.Results showed that protein content of the extracted myofibrillar was 59.27%,the types and composition ratio of amino acids in this protein was every inch and balanced,the content of essential amino acid reached40.90%. The best enzyme for hydrolyzing myofibrillar protein was alcalase. On the foundation of single factors experiment,the optimal hydrolysis conditions for myofibrillar protein hydrolyzed by alcalase was obtained as:enzyme concentration 3500 U / g,p H7.8 and temperature 44 ℃ through the Box- Behnken methodology. After hydrolysis for 6 h under the above conditions,the DH reached 33.17%. The content of peptide < 1000 u reached61.5% by peptide molecular weight distribution,illustrated that myofibrillar proteins hydrolyzed in a high degree by alcalase.