OBJECTIVE To explore whether pachymic acid （Pac） regulates mitochondrial autophagy mediated by the PTEN- induced kinase 1 （PINK1）/Parkin RBR E3 ubiquitin-protein ligase （Parkin） signaling pathway to alleviate myocardial injury in coronary heart disease （CHD） rats. METHODS SD rats were divided into control （Con） group， CHD group， Pac low-dose group （Pac-L group）， Pac high-dose group （Pac-H group）， Pac-H+PINK1/Parkin signaling pathway inhibitor group （Pac-H+3-MA group）， with 10 rats in each group. Except for the Con group， CHD models were established in the remaining groups of rats. After successful modeling， the rats in each group were intraperitoneally injected with the corresponding drugs or normal saline. After continuous intervention for 4 weeks， the left ventricular ejection fraction （LVEF）， left ventricular end-diastolic volume （LVEDV）， left ventricular end-systolic volume （LVESV）， and mean arterial pressure （MAP） of the rats were detected. The levels of creatine kinase isoenzyme （CK-MB）， lactate dehydrogenase （LDH）， cardiac troponin I （cTnI）， and cardiac troponin T （cTnT） in the serum， as well as the levels of tumor necrosis factor-α （TNF-α）， interleukin-10 （IL-10）， IL-1β， reactive oxygen species （ROS）， malondialdehyde （MDA） in the myocardial tissue， and the activities of catalase （CAT） and superoxide dismutase （SOD）， as well as the expression levels of p62， cleaved caspase-3， Parkin， PINK1 proteins and the ratio of microtubule-associated protein 1 light chain 3 Ⅱ （LC3Ⅱ）/LC3Ⅰ ratio were measured. The morphology of myocardial tissue and mitochondrial autophagic vesicles were observed， and the number of mitochondrial autophagic vesicles per unit area and the rate of cardiomyocyte apoptosis were counted. RESULTS Compared with CHD group， LVEF， MAP， IL-10 levels， CAT and SOD activities， p62， Parkin， PINK1 protein expressions， LC3Ⅱ/LC3Ⅰ ratio， the numbers of mitochondrial autophagic vesicles per unit area in the Pac-L and Pac-H E-mail：hzdpft@163.com groups were increased significantly （P＜0.05）； the levels of LVEDV， LVESV， CK-MB， LDH， cTnI， cTnT， TNF-α， IL-1β， ROS and MDA， cell apoptosis rates， and protein expression of cleaved caspase-3 were all decreased significantly （P＜0.05）； and the changes in various indicators were more pronounced in the Pac-H group （P＜0.05）； both groups showed varying degree of improvement in myocardial histopathological morphology. Compared with the Pac-H group， the aforementioned indicators in rats from the Pac-H+3-MA group were all significantly reversed （P＜0.05）. CONCLUSIONS Pac may promote mitochondrial autophagy in cardiomyocytes of CHD rats by activating the PINK1/ Parkin signaling pathway， thereby reducing inflammatory responses and oxidative stress and improving myocardial injury.