This study aimed to identify causes of in-hospital death in ST-segment elevation myocardial infarction (STEMI) patients undergoing percutaneous coronary intervention (PPCI) in the Beijing metropolitan area. A total of 56,763 PPCIs were performed at 56 eligible hospitals between January 1, 2010, and December 31, 2018, among which 1,278 patients died. Causes of death were analyzed and finally adjudicated by a review board. The overall in-hospital mortality rate was 2.25%, ranging annually from 1.96% to 2.48% over the study period. Of these, 1,069 (83.6%) deaths were attributed to disease severity-related causes, mainly cardiogenic shock of 44.4%, mechanical complications of 15.2%, malignant arrhythmia of 8.1% and heart failure of 6.2%. Another 209 (16.4%) patients died from PPCI-related complications, including coronary no-reflow of 8.5%, stent thrombosis of 3.5%, and PPCI-related bleeding of 2.4%. The incidence of PPCI-related death has decreased from 1.02% in 2010 to 0.15% in 2018 (p <0.001). Hospitals in the highest quartile PPCI volume (>130 PPCI annually) had lower incidence of in-hospital death (1.97% vs 2.62%, 2.99%, and 2.56%, p <0.001), disease severity-related death (1.66% vs 2.13%, 2.4%, and 2.17%, p <0.001) and PPCI-related death (0.31% vs 0.48%, 0.59%, and 0.39%, p = 0.003), as compared to those with the first, second and third quartiles of annual PPCI volume. In conclusion, among patients with STEMI and treated with PPCI, in-hospital mortality keeps at a relatively low level in Beijing area. Most deaths are due to pathophysiological deteriorations following STEMI. Hospital PPCI volume remains serve as an important indicator for quality of care.