Aim To evaluate the related factors that affect thrombolysis in myocardial infarction(TIMI) flow after primary percutaneous coronary intervention(PCI) in patients with acute myocardial infarction(AMI). Methods Clinical and angiographic data of AMI patients treated by primary PCI were collected.Relative analysis was completed. Results 75 AMI patients treated by primary PCI were included in the study,60 patients had TIMI 3 flow(60/75,80%),and 15 patients had less than TIMI 3 flow(15/75,20%).Univariate analysis showed that the infarct related artery diameter,times of balloon dilation,stent number, stent diameter,times of stent dilation,history of diabetes mellitus,time from symptom onset to emergency room,catheterization room and flow reopened could affect TIMI flow obviously(p<0.05),multivariate analysis showed that the infarct related artery diameter,times of balloon dilation,history of diabetes mellitus,time from symptom onset to emergency room were independent factors which influenced TIMI flow after primary PCI(p<0.05). Conclusions The infarct related artery diameter,times of balloon and stent dilation,history of diabetes mellitus,time from symptom onset to flow reopened were independent factors which influenced TIMI flow after primary percutaneous coronary intervention in patients with acute myocardial infarction.