Objective To observe the protective effect of Zhilong Huoxue Tongyu Capsule(Zhilong Capsule)on myocardial ischemia reperfusion injury(MIRI)in mice,and explore its regulatory mechanism using metabolomics.Methods Using a random number table method,30 C57BL/6J mice were randomly divided into the following three groups:sham operation group,model group,and Zhilong Capsule group(6.24 g/kg),with 10 mice in each group.In mice in the model group and the Zhilong Capsule group,a mouse MIRI model was established by ligating the left anterior descending branch,while mice in the sham operation group underwent threading without ligation.The Zhilong Capsule group began modeling one week after pre-administration and continued to receive intragastric administration for two weeks after modeling once daily.The cardiac function,including the left ventricular ejection fraction(LVEF)and left ventricular fraction shortening(LVFS),was assessed by color echocardiography.The myocardial fibrosis and apoptosis were observed by Masson staining and TUNEL staining,respectively.Enzyme-linked immunosorbent assay was used to measure the serum contents of lactate dehydrogenase(LDH)and brain natriuretic peptide(BNP).Liquid chromatography-mass spectrometry combined with multivariate statistical method was performed for serum metabolite detection and identification analysis.Results Compared with the model group,the mice in the Zhilong Capsule group exhibited an increase in LVEF and LVFS,a reduction in cardiac tissue structure disorder,a decrease in myocardial fibrosis,a decrease in cell apoptosis rate,and a decrease in serum LDH and BNP contents(P<0.05).Metabolomics result showed that intervention with Zhilong Capsule significantly regulated 30 differential metabolites related to MIRI.Important metabolic pathways involved 20 pathways related to tyrosine metabolism,arginine and proline metabolism,and vitamin digestion and absorption.Conclusion Zhilong Capsule has a protective effect on MIRI,and it may achieve this effect by regulating pathways related to tyrosine metabolism,arginine and proline metabolism,and vitamin digestion and absorption.