Abstract: The method of complex enzyme was used to prepare ACE inhibitory peptides from sea cucumber viscera， and five factors affecting peptides preparation，such as temperature，time，the ratio of solid toliquid， pH and amount of enzyme were studied. The optimal parameters for the preparation of ACE inhibitory peptides were determined through single factor experiment and orthogonal test as follows：temperature at 50℃ ，time for 5 h，pH 7.5 and amount enzyme of 2%. Under these conditions，ACE inhibitory rate was up to 55.4%.