Objective To identify the factors of no-reflow during emergency percutaneous coronary intervention (PCI) in patients with acute ST-segment elevation myocardial infarction (STEMI). Methods A total of 92 patients with acute STEMI treated with PCI were divided into normal reflow group(73 patients ) and no-reflow group (19 patients) from June 2012 to January 2013.The influencing factors of no-reflow were clarified by comparing clinical symptoms of the two groups. Results The no-reflow rate after undergoing emergency PCI was 20.7% in 92 acute STEMI patients.The systolic blood pressure (SBP), type 2 diabetes, troponin T peak, period from disease onset to reperfusion, balloon expansion times and stent number of the target blood vessel were significantly different between the two groups (P<0.05). Multivariate logistic regression analysis identified that low SBP (SBP<100 mmHg, 1 mmHg=0.133 kPa), type 2 diabetes, balloon expansion times, troponin T peak, right coronary artery lesions and period from disease onset to reperfusion were the risk factors for no-reflow during PCI in patients with STEMI. Conclusion No-reflow following emergency PCI in acute STEMI patients is associated with six clinical factors: SBP<100 mmHg, type 2 diabetes, balloon expansion times, troponin T peak, right coronary artery lesions and period from disease onset to reperfusion.