Due to factors such as drought, tides, rainfall and human activities, the temperature of seawater in the nearshore intertidal zone fluctuates greatly, and the organisms such as shellfish living there are susceptible. Therefore, in order to explore the effect of high temperature stress on shellfish, the razor clam (Sinonovacula constricta) was used as the model organism in this study. The control group (24 °C) and the high temperature groups (28 °C, 32 °C) with a stress time of 72 hours were set up to start the comparative experiments. The survival rate, oxygen consumption rate and ammonia excretion rate of the S. constricta were sampled at 0, 6, 12, 24, 48 and 72 h, respectively. The activity of superoxide dismutase (SOD) and the content of malondialdehyde (MDA) in the hepatopancreas and gill of them were determined at the same time. The results showed that the survival rate of S. constricta at 28 and 32 °C were 27.80%±4.15% and 20.00%±2.69%, respectively, which were significantly lower than that at 24 °C 85.60%±1.60%. With the increase of temperature, the oxygen consumption rate and ammonia excretion rate of S. constricta also increased, and reached the maximum value at 32 °C. SOD activity and MDA content in the hepatopancreas and gill tissues increased with the increase of temperature, and showed a trend of first increasing and then decreasing with the extension of time. The results demonstrated that under acute high temperature stress, the physiological metabolic activities of S. constricta intensified, but still maintained a certain survival rate and antioxidant capacity. The study can provide a data reference for the cultivation of new strains of S. constricta with high temperature resistance.