Abstract: The sweet almond protein was prepared with the method of alkali extraction and acid precipitation,and then fractionated as albumin,glindin,globulin and glutelin. The proteins were hydrolyzed as peptides with Alcalase protease and the hydrolysates were filtered through polyethersulfone membrane with different molecular weight cutoffs. The angiotensin-converting enzyme(ACE) inhibitory activities of different molecular weight of almond peptides were measured. The results showed that different molecular weight peptides had different inhibitory activities and the activity increased with the molecular weight reduced. The results also showed that the activity had obviously difference for peptides derived from different proteins,glutelin peptides were highest activity among four proteins and the IC50 of ACE inhibitory activity was(96.21±0.06) μg/m L for glutelin peptide with molecular weight below 1 ku.