This experiment was conducted to investigate the effects of adding selenium yeast (SY) in a basal diet on the growth performance, antioxidant capacity and selenium content in the body wall before and after the aestivation of Apostichopus japonicus. This experiment was carried out in 500 L plastic tanks. Two-day-old Apostichopus japonicus with an initial body weight of (140.00±0.21) g were divided into 5 groups, which fed the basal diet with SY at 0, 0.5, 1.0, 1.5 and 2.0 mg/kg (the measured total selenium contents in diets were 0.40, 0.94, 1.55, 2.08 and 2.40 mg/kg, respectively), and each group had 3 replicates, each replicate had 11 to 14 Apostichopus japonicas. Apostichopus japonicus were fed twice daily to apparent satiety. The experiment included two phases, and total 105 d. The phase 1: the feeding experiment lasted for 45 days, at the end of the feeding experiment, weight gain rate, antioxidant ability and selenium content in body wall were detected; the phase 2: at the end of aestivation (there is a small amount of intake and obvious signs of activity; aestivation lasted for 60 d), body wall were sampled for the detection of selenium content. The results showed as follows: 1) with the increase of SY supplementation, growth and antioxidant ability of Apostichopus japonicas increased firstly and then decreased. When the SY supplementation was 0.5 mg/kg, the weight gain rate was the highest, and significantly higher than that in 1.0 mg/kg group (P<0.05), but had no significant difference compared with other groups (P>0.05). The activities of superoxide dismutase (SOD), glutathione transferase (GSH-ST), glutathione peroxidase (GSH-Px) and total antioxidant capacity (T-AOC) showed decreasing trend with the increase of SY supplementation, and the activities of SOD, GSH-Px and GSH-ST in 0.5 mg/kg group had no significant difference compared with the control group (P>0.05), but were significantly higher than those in 2.0 mg/kg group (P<0.05); the content of malonaldehyde (MDA) in 0.5 mg/kg group had no significant difference compared with 1.0 mg/kg group (P>0.05), but was significantly higher than that in other three groups (P<0.05); the activity of oxidase (CAT) in 0.5 mg/kg group was significantly higher than that in control group (P<0.05), but had no significant difference compared with other three groups (P>0.05). 2) The selenium content in the body wall of Apostichopus japonicus showed an increasing trend with SY supplementation increased before and after the aestivation. Although the selenium content in the body wall was decreased after aestivation, the selenium retention rate was still above 50% in all groups. The selenium retention rate in 1.0 mg/kg group was the lowest, which was 51.12%, and that in 2.0 mg/kg group was the highest, which was 91.38%. It can be concluded that the supplementation of 0.5 mg/kg SY in the diets can enhance the growth performance, antioxidant capacity and selenium content in the body wall, while middle and high supplementation levels of SY (1.0 to 2.0 mg/kg) can decrease weight gain rate and antioxidant capacity, although the selenium content in the body wall have an decreasing trend at the end of aestivation, all the groups reached the standard of selenium-enriched Apostichopus japonicas (aquatic animal selenium-enriched standard is 0.5 to 1.0 mg/kg selenium).