Objective To investigate the risk factors of in-hospital deaths in the patients undergoing emergency percutaneous coronary intervention due to acute occlusion of the left main coronary artery. Methods This study retrospectively analyzed the clinical data of patients diagnosed with myocardial infarction caused by acute occlusion of the left main stem, who were admitted to Chinese PLA General Hospital through the emergency green channel coronary angiography examination from January 2011 to January 2021. According to the death of the participant during hospitalization, they were divided into death group and survival group. By comparing the clinical data and coronary imaging reading of the two groups and analyzing the association between various clinical variables and mortality of patients during hospitalization, the risk factors was screened. SPSS 19.0 was used for statistical analysis. Data comparison between two groups was performed using t-test, rank sum test orχ² test depending on data type. Multivariate analysis was performed using logistic regression. Results Of all patients with acute occlusion of the left main stem, 22 were right-dominant. The death group had more patients with no right coronary to provide collateral circulation and with postoperative thrombolysis in myocardial infarction (TIMI) level 0-2 blood flow, the difference being statistically significant[6 (85.71%) vs 1 (6.67%), 5(71.43%) vs 4(26.67%); both P<0.05]. There was no significant difference in other indicators. Telephone follow-up confirmed 1 death (4.54%) after 20 days, interventional treatment of the right coronary artery in 1 rehospitalized patient (4.54%) at 3 postoperative months, interventional treatment of in-stent restenosis in the left main coronary artery in 2 patients (9.09%) at postoperative 4 and 6 years respectively, and 1 death (4.54%) due to lung cancer at postoperative 6 years, and no severe adverse cardiovascular events in 10 patients (45.45%). Logistic univariate regression analysis showed that cardiogenic shock on admission, no right coronary collateral circulation, and postoperative TIMI level 0-2 blood flow were risk factors for death during hospitalization (P<0.05). Multivariate regression analysis showed no right coronary collateral circulation was an important predictive factor for death due to acute occlusion of the left main coronary artery during hospitalization. Conclusion Cardiogenic shock on admission, no right coronary to provide collateral circulation, postoperative TIMI flow level 0-2 are important predictors of death during hospitalization in patients receiving emergency percutaneous coronary intervention for acute occlusion of the left main stem, and right coronary collateral circulation is a protective factor for patients with in-hospital death.