Objective:　To　prepare　and　characterize　antioxidant　peptides,　shark　skin　gelatin　was　hydrolyzed　with　acid　protease.　Methods:　The　purification　steps　involved　ultrafiltration,　ion　-exchange　chromatography　on　SP　-Sephadex　C　-25,　gel　filtration　chromatography　on　Sephadex　G-50　and　RP-HPLC,　and　the　in　vitro　antioxidant　activity　and　cryoprotective　activity　of　antioxidant　peptides　were　further　studied.　Result:　Three　antioxidant　peptides,　designated　B-IIIa,　B-IIIc　and　B-IIId,　were　isolated　from　gelatin　hydrolysate　of　shark　skin.　Their　half-inhibitory　concentrations　for　scavenging　DPPH　free　radical　respectively　were　63.56　μg/mL,　98.70　μg/mL　and　100.27　μg/mL,　and　for　ABTS　free　radicals　respectively　were　82.34　μg/mL,　90.97　μg/mL　and　84.58　μg/mL.　However,　their　activities　of　inhibit　lipid　peroxidation　were　much　weaker.　The　low-temperature　bacteria　protection　experiment　results　showed　that　all　of　these　three　peptides　could　increase　the　E.　coli　survival　rate　in　the　frozen　enviroment,　in　which　survival　rate　of　B-IIIc　and　B-IIId　group　could　reach　81.88%　and　87.50%,　respectively.