Temperature has a significant effect on the growth, reproduction, distribution and abundance of sea cucumbers (). The suitable temperature range for this species is 5-20℃, and the optimum growth range is 10-16℃, which fluctuates depending on size. When the water temperature exceeds the optimal range, stops feeding and goes into aestivation. In recent years, as global warming has intensified, slow growth, malformation and high mortality of marine animals have been observed frequently because of high temperatures. High seawater temperatures during summer 2013 resulted in significant economic losses in the A. japonicus resistant to high temperatures is required urgently. In this study, we used 1-year-old juveniles (13.6 g±1.8 g) from a directed breeding population (F3 group) and a wild population (C group) as the experimental animals. High temperatures as in ponds in summer were imitated (25℃, 27℃, 29℃, 31℃, 32℃ and 33℃, increasing by 0.5℃ every 12 h). The activities of superoxide dismutase (SOD), catalase (CAT), acid phosphatase (ACP), alkaline phosphatase (AKP), lysozyme (LSZ) and total antioxidant capacity (T-AOC) of in F3 and C groups were determined and compared after 12 h thermal stimulus at different temperatures. The results showed that temperature had a significant influence on the SOD, CAT, ACP, AKP and LSZ activities, and T-AOC. The SOD activities ofthe F3 and C groups initially showed an upward trend, but declined as the temperature increased from 25℃ to 33℃. The activity of SOD in the F3 group was significantly higher than in group C (<0.05) at 31℃ and 32℃.The CAT activity and T-AOC declined in both groups as temperature increased from 25℃ to 33℃. The CAT activity in the F3 group was higher than in group C at every temperature level, and the difference was significant when the temperature was 27℃, 29℃, 31℃ and 33℃ (<0.05). The T-AOC in group F3 was significantly higher than in group C (<0.05) at temperature ranges from 25℃ to 33℃. The ACP and AKP activities in both groups declined as temperature increased; the ACP activity in group F3 was significantly higher than in group C (<0.05), except at 31℃; and the AKP activity in group F3 was significantly higher than in group C (<0.05) when the temperature was 25℃, 27℃ and 31℃. The LSZ activity showed an initial upward trend and then declined as the temperature increased in both groups; the activity in the F3 group was significantly higher than in group C at 27℃, 29℃ and 31℃. The results indicated that the immune capacity of thermotolerant to high-temperature stress has improved after three generations of directed breeding. This study provides useful information for further research on selective breeding of . The rate of global warming is increasing, and the average temperature of the earth's surface is predicted to rise by 1.5-6.0℃ by the end of the present century, according to the 2007 report by the Intergovernmental Panel on Climate Change (IPCC). Therefore, biological studies of organisms, including , under high-temperature stress are urgently required.