Abstract: The rules of the protein hydrolysis and the tyrosine content were studied. The changes of amino nitrogen,TCA-soluble nitrogen index(TCA-NSI),free amino acid,degree of hydrolysis(DH),tyrosine and protein molecular weight were analyzed. Results showed that tyrosine increased with the increase of amino nitrogen,TCA-NSI,free amino acid,DH in pehtze during Shaoxing sufu fermentation. The mainly degraded proteins in the first 40 days were 7S and 11 S proteins,while the mainly degraded substance after 40 days was low molecular protein. Correlation analysis indicated that the Pearson correlation coefficient of the content of free tyrosine and DH was higher than that of others. Besides this,the TCA-NSI,DH and free tyrosine were higher in sufu with white particles than those in sufu without white particles,so it could be concluded that the white particles in sufu were formed due to the excessive hydrolysis of proteins. This research could provide reference to control white particles in Shaoxing sufu.