Abstract:To investigate the effects of ozone treatment on the levels of oxidative stress markers and the state of the antioxidant defense system of mitochondria in frozen kiwifruit，the kiwifruit was first treated under ozone for consecutive 7 d and stored in cold storage（0-1 °C，relative humidity of 90%-95%）.The respiration rate，decay rate，malondialdehyde，hydrogen peroxide，superoxide anion，glutathione，ascorbic acid，dehydroascorbic acid content，and glutathione peroxidase activity in both the control and the treated groups were measured.The microstructures of mitochondria and cytoderm in kiwifruit were also observed by transmission electron microscopy.The results showed that ozone treatment enhanced the activities of mitochondrial enzymes related to enzymatic antioxidant metabolism and regulated the redox state of postharvest kiwifruit，thus effectively inhibiting the overproduction of reactive oxygen species and the production of malondialdehyde.Ozone treatment led to an increase in reactive oxygen species accumulation，which in turn activated the defense mechanism against fruit oxidative stress，regulated the mitochondrial antioxidant system，reduced the respiration rate and decay rate of kiwifruit，and delayed the ripening and aging of postharvest kiwifruit.