Seven edible sea cucumbers with low economic value were hydrolyzed by three proteases including protamex， flavorzyme and papain for 4， 8 and 12 h to obtain the sea cucumber extracts， respectively. Assays for reducing power， hydroxyl radical scavenging capacity and oxygen radical absorption capacity were conducted to determine their antioxidant activities. The different sea cucumber extracts were classified in terms of extract yields， protein recovering ratios， and antioxidant activities by clustering analysis. The extract yields and protein recovering ratios of cucumaria frondosa， acaudina leucoprocta， holothuria tubulosa， holothuria scabra， and thelenata anax extracts were superior to those of stichopus variegates and holothuria keferstein extracts. And the antioxidant capacity of extract of cucumaria frondosa was the highest. The extract yields， protein recovering ratios， and antioxidant activities of the sea cucumber extracts prepared by protamex were the higest among all extracts. In terms of optimal extraction parameters， the extract yields were 41.24%-55.57%. The protein recovering ratios were 65.06%-98.4%. The antioxidant activity values including reducing power values， OH values and ORAC values were 3.41-3.41 μmol trolox equiv/g dry sea cucumber， 28.83-96.65 μmol trolox equiv/g dry sea cucumber， 38.99-133.08 μmol trolox equiv/g dry sea cucumber， respectively. The results are beneficial for processing edible sea cucumbers to obtain valuable products in food industry.