Objective To investigate the myocardial repair after emergency and elective percutaneous coronary intervention (PCI). Methods A retrospective study was conducted on 97 patients with myocardial infarction admitted in our department from January 2018 to February 2019. According to the timing of PCI, they were divided into emergency PCI group (n=50) and selective PCI group (n=47). Cardiac function and myocardial repair were evaluated and compared by cardiac magnetic resonance imaging (CMRI) in 3 months after operation. The levels of troponin I (TnI), brain natriuretic peptide (BNP) and creatine kinase isoenzyme-MB (CK-MB) were compared before and 3 months after operation. SPSS statistics 22.0 was used for data analysis. Student′s t test or Chi-square test was applied to make comparison between 2 groups according to the different data types. Pearson correlation analysis was also employed. Results Compared with before operation, left ventricular end-diastolic volume (LVEDV), left ventricular end-systolic volume (LVESV), preoperative myocardial mass, visual score of myocardial volume, abnormal wall motion score, and levels of TnI, BNP and CK-MB were all improved in both groups, and the indicators were lower in the emergency PCI group than the selective PCI group [(108.41±21.15) vs (126.61±22.05)ml, (59.55±14.41 vs (65.54±11.64) ml, (6.84±2.15) vs (9.16±3.00)g, (6.03±2.11) vs (8.15±2.32) score, (3.01±1.16) vs (4.41±1.25) score, (106.84±29.98) vs (122.16±32.11)g/L, (1.00±0.34) vs (1.24±0.54)ng/L, (32.21±5.44) vs (35.49±4.48) U/L]. Pearson correlation analysis showed that myocardial quality was positively correlated with myocardial volume visual score, wall motion abnormality score, LVEDV and LVESV (r=0.411,0.354,0.306 and 0.341, P<0.05). Conclusion Emergency PCI can significantly improve myocardial function and repair in patients with myocardial infarction.