The present invention provides an angiotensin converting enzyme inhibitor, which is prepared from a streamed fish solution digested by flavourzyme. The angiotensin converting enzyme inhibitor of the present invention can help lower blood pressure and control high blood pressure it can be used as a therapeutic and prophylactic medicine and health care products本發明提供一種血管收縮素轉換酶(Angiotensin converting enzyme,ACE)抑制劑,其係由風味蛋白酶(flavourzyme)分解魚類蒸煮液製備而成。本發明之血管收縮素轉換酶抑制劑具有降低血壓及防止血壓升高之功效,能作為用於製備治療或預防高血壓之藥物或保健食品。