Angiotensin-Converting Enzyme 2 (ACE-2) is an integral membrane protein and a zinc metalloprotease of the ACE family, the ACE family includes somatic and germinal ACE. ACE-2 cleaves angiotensins I and II as a carboxypeptidase, ACE-2 converts angiotensin I to angiotensin 1-9, and angiotensin II to angiotensin 1-7. ACE-2 is also able to hydrolyze apelin-13 and dynorphin-13 with high efficiency. ACE-2 can be high expressed in testis, kidney and heart, in colon, small intestine and ovary at moderate levels. Captopril and lisinopril as the classical ACE inhibitor don’t inhibit ACE-2 activity. ACE-2 may play an important role in regulating the heart function.