Objective To investigate the protective effects of essential oil and extract of Cinnamomum migao on myocardial injury in rats. Methods SD rats were randomly divided into normal control group（CG）， model group（MG），compound salvia miltiorrhiza group（FFDS），nicorandil group（Nic），low dose essential oil group（GO⁃1），high dose essential oil group（GO⁃2），low dose extract group（GE⁃1）and high dose extract group （GE⁃2），with 11 rats in each group. Rats in each group，except those in CG，swam exhaustively with ice water for 14 days，and ISO（50 mg/kg）was injected subcutaneously at multiple points in the neck on the 12th day for consecutive 3 days to establish a myocardial ischemia injury model. After model establishment，the corresponding drugs were intragastrically administered twice a day for 7 days. Lead Ⅱ ECG was collected from the rats before and after treatment to observe the pathological changes of abdominal aorta and myocardium stained with HE and Masson after treatment. Myocardial markers AST，LDH，CK⁃MB，cTn⁃ I，inflammatory cytokines IL⁃6，TNF⁃ α，SOD activity and MDA content were measured by kits. Results The main ECG findings of lead Ⅱ in the model rats were supraventricular arrhythmia，inflammatory cell infiltration in myocardial tissue and glial deposition in interstitial cells，indicating that the rat myocardial injury model was successfully constructed. Compared with those in CG， rats in MG had ST segment elevation，accompanied by arrhythmia，a large number of cell necrosis and inflammatorycell infiltration in myocardial tissue，and collagen fiber and connective tissue proliferation were observed；LDH and AST activities and CK⁃MB，cTn⁃1，IL⁃6，and TNF⁃α contents in serum were significantly higher（P < 0.01）； SOD activity was decreased（P < 0.05），and MDA expression was significantly higher（P < 0.05）. Compared with those in MG，pathological damage of myocardial tissue，abdominal aorta and ECG changes were significantly improved in FFDS，Nic，GO⁃1，GO⁃2，GE⁃1 and GE⁃2. Compared with that in GE⁃1 and GE⁃1，the expression of cTn⁃1 and MDA in GO⁃1，and the level of AST and IL⁃6 in GO⁃2 were inhibited；the content of CK⁃MB and TNF⁃α in GE ⁃ 1，and the activity of LDH in GE ⁃ 2 were decreased and the activity of SOD was increased. Conclusion Both essential oil and extract of Cinnamomum migao can repair injured myocardial tissue by alleviating oxidative stress injury，inhibiting the expression of myocardial injury markers and inflammatory response，and the extract site has more advantages in reducing the expression of LDH，CK⁃MB，TNF⁃α and increasing the activity of SOD.