Dibutyl phthalate (DBP), a kind of plasticizer, had been included in the priority control pollutants list in China. The impact on marine organisms has caused widespread concern. At present, the research on the impact of DBP on marine organisms focuses on the growth, reproduction, and development of plankton, crustaceans, and fish. There are limited studies on the effects of antioxidant indicators in shellfish. Biochemical indicators such as antioxidants and disease resistance of organisms are important indicators of the degree of stress in response to pollutants and are widely used in ecotoxicology research. As one of the main varieties of seawater shellfish cultured in China, has a strong bioaccumulation in the marine environment and can be used as a biomonitoring species for environmental pollution. To study the changes of the antioxidant defense system, superoxide dismutase (SOD) and catalase (CAT) activity, and malondialdehyde (MDA) content in the gills and visceral mass of at five concentrations of DBP (0 mg/L, 100 mg/L, 200 mg/L, 280 mg/L, and 360 mg/L), with two stages of clear water flushes, were measured. This was to explore the effect of DBP stress on the biological indicators of and to determine whether the function of the body could be restored by the flushes of clear water. The experimental results show that the activities of SOD, CAT, and MDA content in gills and visceral mass of were not identical. Under DBP stress, SOD activity in gills and visceral mass was basically increased, then decreased, and then increased; CAT activity was decreased first and then increased; MDA content generally increased. When they were transferred to clean seawater, the activity of SOD in the gills and visceral mass of showed a trend of decreasing first and then increasing, and CAT activity was increased first. After CAT activity in the visceral mass decreased, and the MDA content in the gills increased, the visceral mass showed a trend of increasing CAT activity first and then decreasing, and the concentration-effect and time-effect were more obvious. This indicated that, under DBP stress, the body was induced to produce reactive oxygen free radicals to reduce the damage of free radicals to cells. With the prolongation of stress time and the increase in concentration, the activity of SOD and CAT in most concentration groups showed a trend of decreasing first and then increasing, which may be because of the inability of the antioxidant system in to remove excess oxygen free radicals in time. When the DBP stress exceeds the capacity of the body (which causes a certain amount of oxidative damage to the cells), SOD and CAT activity is inhibited, and the tendency to increase may be related to the metabolic consumption of DBP and the self-repairing regulation of . It can induce the body to perform lipid peroxidation, which will cause the increase in MDA content. This damage is difficult to return to normal with a release of clean seawater. Although SOD and CAT activity did not show complete synchronization, this phenomenon is consistent with the organism's antioxidant enzyme response mechanism. In short, the change of antioxidant enzyme activity in marine organisms is a dynamic process, which may be affected by many factors such as environment, concentration, biological individual, and tissue differences. Therefore, it is necessary to comprehensively consider the response mechanism. The results of this paper evaluated the effect of DBP on from the perspective of oxidative damage, and provided reference data for the comprehensive understanding of the mechanism of DBP on marine organisms in the future, and provides a scientific basis for aquaculture health and risk assessment of marine shellfish.