The effects of steam pressure and holding time on the dissolution rate， free amino group content， and angiotensin converting enzyme （ACE） inhibition rate of fish skin protein was studied. The relative molecular mass distribution of the protein hydrolysates of fish skin before and after steam explosion pretreatment was further characterized. The results showed that steam explosion treatment could effectively promote the dissolution and degradation of fish skin protein， and increase the ACE inhibition rate of the enzymolysis product. Under the optimal condition（0.6 MPa for 0.5 min）， the dissolution rate and the free amino group content of fish skin protein was 45.55% and 2.79 mmol/L， respectively， which was 5 and 8 times higher than that of the untreated sample. The ACE inhibition rate of the fish skin hydrolysate was 79.88%， mainly distributed below 4 ku.