OBJECTIVE： To investigate the effects of trimetazidine before percutaneous coronary intervention （PCI） on oxidative stress indexes of acute myocardial infarction （AMI） patients after surgery. METHODS： Medical information of 100 AMI patients underwent PCI were analyzed retrospectively and divided into control group （50 cases） and observation group （50 cases） according to drug use. Both groups were given Clopidogrel bisulfate tablet+Aspirin enteric-coated tablets 1 d before PCI， taking at a draught. Based on this， control group was given Tirofiban hydrochloride sodium chloride injection during PCI according to disease condition； they were given ACEI inhibitor or angiotensin receptor blocker （ARB）， clopidogrel， aspirin and low molecular weight heparin. Observation group was additionally given Trimetazidine hydrochloride tablet 20 mg orally， 3 times a day， before PCI on the basis of control group. Treatment course of 2 groups lasted for 3 weeks. The serum levels of SOD， MDA， NO and NOS， the occurrence of ADR were observed in 2 groups before treatment and 1，3 weeks after treatment. RESULTS： After 1 week of treatment， SOD of 2 groups were significantly lower than before treatment， and the observation group was significantly higher than the control group，with statistical significance（P＜0.05）； after 3 weeks of treatment， SOD of observation group was significantly higher than before treatment and control group， with statistical significance （P＜0.05）； but there was no statistical significance in control group before and after treatment （P＞0.05）. After 1 week of treatment， MDA of 2 groups were significantly higher than before treatment， with statistical significance （P＜0.05）， but there was no statistical significance between 2 groups （P＞0.05）. After 3 weeks of treatment， MDA of observation group was significantly lower than before treatment and control group， with statistical significance （P＜0.05）， there was no statistical significance in control group before and after treatment （P＞0.05）. After 1 week of treatment， NO and NOS levels of control group were significantly higher than before treatment， while NO and NOS of observation group were significantly lower than before treatment； the observation group was significantly lower than the control group， with statistical significance （P＜0.05）. 3 weeks after treatment， NO and NOS of 2 groups were significantly lower than before treatment， and the observation group was significantly lower than the control group， with statistical significance （P＜0.05）. There was no statistical significance in the incidence of ADR between 2 groups （P＞0.05）. CONCLUSIONS： The application of trimetazidine before PCI can reduce oxidant stress indexes of AMI patients with good safety.