Abstract: Objective To investigate the effect of urokinase thrombolysis combined with percutaneous coronary intervention(PCI)in patients with acute ST segment elevation myocardial infarction(STEMI). Methods A total of 150 STEMI patients were randomly divided into control group and observation group, with 75 cases in each group. The control group was treated with emergency PCI, while the observation group was treated with urokinase thrombolysis combined with emergency PCI. Blood grading of thrombolysis in myocardial infarction(TIMI), myocardial perfusion and cardiac function levels of the two groups were compared in the two groups. Results Ratio of patients with the TIMI level 3 blood flow in the observation group was 85.33%, ratio of patients with the ST-segment regression was 90.67%, and ratio of patients with the TMPG level 3 blood flow was 68.00%, which were higher than those in the control group(69.33%, 72.00% and 52.00%, respectively); the Corrected TIMI Frame Count(CTFC)was significantly lower than the control group(P<0.05). At 1 and 3 months after surgery, the left ventricular end-diastolic diameter(LVEDD)in the observation group was significantly lower than that in the control group, and the left ventricular ejection fraction(LVEF)was significantly higher than that in the control group(P<0.05). Conclusion Thrombolytic therapy by urokinase combined with emergency PCI can improve myocardial microcirculation perfusion and cardiac function in patients with acute STEMI.