Aim To investigate the risk factors of acute kidney injury （AKI） in patients with acute myocardial infarction （AMI）. Methods 728 patients with AMI were divided into two groups: AKI group and non AKI group. Clinical characteristics were compared in the two groups. The independent risk factors of AKI in patients with AMI were analyzed. The effect of emergency percutaneous coronary intervention （PCI） on AKI occurrence was assessed in patients with AMI. Results In 728 AMI patients, AKI was found in 152 patients （20.9%）. Compared with non AKI group, the differences of the eleven indexes of AKI group were statistically significant （P<0.01）, these indexes including: age, history of diabetes, mean arterial pressure, systolic blood pressure, heart rate, cardiac function Killip classification, left ventricular ejection fraction, base estimated glomerular filtration rate （eGFR）, ST-segment elevation myocardial infarction, β-blocker and ACEI/ARB application. Multivariate Logistic regression analysis showed that age, history of diabetes, admission systolic blood pressure, degree of cardiac function, left ventricular ejection fraction, base eGFR, unused ACEI/ARB medication were independent risk factors of AKI occurrence in patients with AMI. In 378 cases of ST-segment elevation myocardial infarction, 256 patients underwent emergency PCI. Statistical analysis showed that the incidence of AKI was significantly higher in patients with non-PCI than that in patients with emergency PCI （39.3% vs 19.5%, P<0.01）. Conclusions AKI is a common complication of AMI, which is related to many factors. Emergency PCI can reduce the incidence of AKI in patients with ST segment elevation myocardial infarction.