The invention discloses polypeptide of Phascolosoma esculenta which is a polypeptide segment prepared through hydrolysis of extracted protein of the Phascolosoma esculenta. The protein of the Phascolosoma esculenta comprises water-soluble protein, waterinsoluble protein and a mixture thereof. The hydrolysis method comprises protease hydrolysis, acid hydrolysis and alkali hydrolysis. The polypeptide of the Phascolosoma esculenta can be used for inhibiting angiotensin converting enzyme (ACE), so the polypeptide can be used for preparing antihypertensive medicines, and a new way for effectively utilizing the Phascolosoma esculenta is opened up.