Abstract: In order to exploit the proteins from Platycephalus indicus, the preparation technology of peptides with Angiotensin converting enzyme (ACE) inhibition activity by hydrolyzing protein from Platycephalus indicus enzymatcally using ACE inhibition model in vitro as index was studied.The suitable enzyme was selected according to the hydrolysis process of tested enzymes.The key factors were examined by single factor experiment. The optimal hydrolysis condition was established using respond surface methodology. The relative molecular weight distribution of active peptides was determined by gel filtration chromatography.Results showed that Alcalase was the suitable enzyme for hydrolyzing proteins from Platycephalus indicus to prepare peptides with ACE inhibition activity.The optimal hydrolysis condition were as follows:temperature of 48.9℃, pH of 7.93, the amount of enzyme was 32396.6 U/g·pro.And solid-liquid ratio was 1:5 (g/mL), duration time was 2.5 h.The IC₅₀ of hydrolysate prepared under these conditions was 0.269 mg/mL. Three fractions were obtained when applying hydrolysate on Sephadex G-15 column, the relative molecular masses were 635, 258 and 67.The ACE inhibition activity of fraction 2 (C=0.74 mg/mL) was relative higher than the others, reaching 89.09%.