Abstract: Preparing angiotensin I2converting enzyme inhibitors derived from the enzymatic hydrolysate of Acetes chinensis was discussed in this paper. To get the optimal conditions of peptic hydrolysis we did orthogonalty trials with the ACE inhibitory ratio in vitro being the index. The hydrolysate with IC50 being 0. 65 mg?mL -1 was gained under the conditions of pH 2. 4 , temperature 41 ℃, enzymatic hydrolysis time 3 hours , enzymatic concentration 900 U?g 1 substrate and substrate concentration 8 %. The hydrolysate was filtrated with a Sepahdex G225 column , the fraction with the highest ACE inhibitory activity was collected and filtrated with a Sephadex G215 column , and the fraction with the highest activity was collected again , their IC50 were found to be 0. 084 mg?mL -1 and 0. 046 mg?mL -1 , respectively. After purification the content of hydrophobic amino acids tended to increase in the amino acids composition. Molecular weight distribution of the highest ACE inhibitory activity fraction of Sephadex G215 gel chromagraphy was located between 700 and 1900.