Abstract: It was conducted that the Box- Behnken response surface design experiment used flesh paste which were prepared of catfish by- products( fish head,skin,bones and meat,etc.) as test object and obtained rate of polypeptide and calcium dissolution rate as examining index to explore how the pepsin digestion time,enzyme dosage and liquid / material impacted the hydrolysis effect. The result showed that the optimal process conditions were liquid / material 6.73 ∶ 1,enzyme dosage 7000 U / g,hydrolysis temperature 37 ℃,p H value 3.0,reaction time6 h. The obtained rate of polypeptide was 43.07% and calcium dissolution rate was 44.62% in the obtained hydrolyzate from hydrolysis flesh paste under optimum conditions.