Abstract: This paper makes use of orthogonal test to confirm the optimum conditions for hydrolyzing casein by using immobilized enzyme,and studies the process and conditions for extraction and purification from hydrolysate to produce CPP.The results of CPP produced by ourselves are as follows:The molecular weight of Q -CPP is 5000, whose content is 1l%.The molecular weight ofβ -CPP is 3300,whose content is 4%.The total phosphorus is 3.64%.The total nitrogen is 6.97%.The value of N/P is 4.23.