Abstract: To explore the quality changing mechanism in metabolic suppression of post-harvest live scallop,superoxide dismutase(SOD)and catalase(CAT)in different soft tissues were taken as indicators of quality change during live dry-storage of scallop(Patinopecten yessoensis)for 3 days. The raw live scallops were hand-dived on the treatment day. The treatment was carried out at 4℃ and soft tissues were separated into mantle,gonad,striated muscle,gill and visceral mass. The SOD and CAT activities were detected in all tissues,indicating that the SOD activity of striated muscle,gill and visceral mass was high and the CAT activity of gill and visceral mass was higher than other tissues. SOD,CAT,ATP and ATP-related compounds were maintained during the initial stage of 1 d. From 1 to 3 days was the fluctuation period,the SOD activity of each soft tissue increased significantly(P<0.05),and the contents of CAT,ATP and related substances,pH,and glycogen contents changed significantly(P<0.05). From the contents of ATP and its related substances,it was slightly reduced after during chilling dry storage in 3 days,and its vitality remained good,except for ADP,AMP and AdR,no degradation products of ATP were detected. The contents of glycogen decreased from 21.5 mg/g to 19 mg/g and pH declined from 7 to 6.7. Besides,the mass loss rate of scallops increased significantly to 8% by the 3 rd day. These findings suggest that the post-harvest quality-changing mechanisms of live scallops had different in successive stages. Antioxidant enzyme SOD and CAT activities in scallop soft tissues showed significant changes(P<0.05),and SOD was particularly significant.