The present research was undertaken in order to study the effects of ozone on ROS and disease resistance of apricot fruits. Apricot fruits of "Saimaiti" was fumigated with ozone at 200 mg/m3 and stored in cold storage at (1.0±0.5) ℃. Natural incidence， MDA， cell membrane permeability， O₂-· production rate， H2O₂， CAT， SOD， POD， APX of apricot fruit were determined every seven days during storage. The results show that 200 mg/m3 ozone treatment could significantly reduce the natural morbidity of apricot fruit. On day 49 of storage， compared with the control group， the natural incidence in ozone-treated apricot fruits were 17.0%， which were reduced by 61.94% (P<0.05). Ozone increased the activities of CAT， SOD， POD and APX， effectively reduced H2O₂ content and O₂-· production rate， balance the antioxidant system of apricot fruit， delay the increase of MDA and cell membrane permeability， and slow down the degree of membrane lipid peroxidation. At the end of storage， the activities of CAT， SOD， POD， APX of the ozone-treated group were 47.5， 4.14， 1.98 U and 12.0 U， respectively， which were 1.48， 1.14， 1.15 and 1.58 times as high as those in the control group. Compared with the control group， the H2O₂ and O₂-· production rate in ozone-treated apricot fruits were 22.04 μmol/g， and 264.44 nmol/min·g， which were reduced by 20.61% and 37.04% (P<0.05). It shows that 200 mg/m3 ozone could regulate the activity of enzymes related to active oxygen metabolism and enhance the disease resistance of postharst apricot fruits. It is expected to provide theoretical reference for ozone's widely used storage and preservation of fruits and vegetables.