Fresh porcine brain was used as raw material to prepare porcine brain polypeptide using enzymatic hydrolysis of pepsin， trypsin and lipase. Culture conditions of NE-4C for porcine brain polypeptide and its proliferation were studied. The molecular weight distribution of porcine brain polypeptide was compared by efficient gel permeation chromatography. Orthogonal test was used to study the effects of trypsin addition amount， enzymolysis temperature， pH value and time on proliferation activity of porcine brain polypeptide. The results showed that proliferative activity of NE-4C was enhanced by 5 mg/mL trypsin hydrolysate. Small molecular weight polypeptides below 500 u trypsin hydrolysate accounted for 72.09% in total peptides， higher than that of pepsin and compound enzyme hydrolysate. Proliferative activity of porcine brain products hydrolyzed by trypsin may be related to its higher proportion of low molecular weight peptides. The optimal enzymatic hydrolysis parameters of porcine brain polypeptide were the enzyme dosage 25 mg， enzymolysis time 4 h， enzymolysis temperature 45 ℃， pH 7.5. Under optimal conditions， the proliferative activity of NE-4C was 0.161.