The present study investigated whether an acute temperature change affected hemolymph antioxidant enzyme activities and lipid peroxidation in ark shell Scapharca subcrenata transferred from 22°C to 17°C, 27°C, and 32°C for 72 h and then transferred back quickly to 22°C for a 6-h recovery period. Superoxide dismutase (SOD) and glutathione peroxidase (GPX) activities and malondialdehyde (MDA) contents [in cell-free hemolymph (CFH) and hemocyte lysate (HL)] were chosen as biomarkers of acute temperature stress. The results demonstrated that CFH and HL SOD activities decreased significantly (P < 0.05) after ark shells were exposed to 32°C for 72 h and returned to normal temperature. Glutathione peroxidase activity in CFH of ark shells exposed to 32°C increased significantly (P < 0.01) at 12 h, but then decreased significantly (P < 0.01) at the end of the recovery period. Malondialdehyde contents in the CFHandHL of stressed ark shells, regardless of temperature (17°C, 27°C, or 32°C), were lowest at 1 h of the recovery period, and recovered completely by the end of the experiment. In contrast, no difference was observed in CFH or HLMDA contents between the 17°C and 27°C groups. In conclusion, S. subcrenata had high tolerance to an acute decrease and increase in seawater temperature, but oxidative stress in ark shell hemolymph increased significantly with temperature and time, such as 32°C and greater than 72 h.