Aim To investigate the predictive value of platelet to lymphocyte ratio (PLR) in myocardial reperfusion blood flow and major adverse cardiac and cerebrovascular events (MACCE) in patients with acute ST-segment elevation myocardial infarction (STEMI). Methods Clinical and angiographic data of 181 patients with STEMI who received direct PCI in our hospital during the period of hospitalization were retrospectively analyzed. According to the ROC curve to determine the diagnosis of no reflow in the PLR standard, the selected patients were divided into high PLR group and low PLR group, and the clinical data, incidence of MACCE during hospitalization period and follow-up in the two groups were compared. Results ROC curve analyzed the relationship between preoperative PLR and postoperative TIMI blood flow, and PLR≥162.72 predicted intraoperative no-reflow with a specificity of 85.5% and a sensitivity of 84.62%(AUC＝0.5,5%CI was 0.776～0.883, Z＝6.611, P＜0.001). All patients were divided into two groups including high PLR group (PLR≥162.72, n＝48) and lower PLR group (PLR＜162.72, n＝133), there were no significant differences in clinical data between the two groups. Compared with patients in low PLR group, patients in high PLR group had higher peak levels of creatine kinase-MB (313.55 ± 212.76 U/L vs. 216.64 ±152.41 U/L, P＝0.001), lower left ventricular ejection fraction (48.58%±7.30% vs. 51.66%±6.82%, P＝0.009), and higher incidence of MACCE in-hospital (20.83% (10/48) vs. 9.77% (13/133), P＝0.049). During a mean follow-up of 6~72 (25.57±18.72) months, a total of MACCE occurred in 28 cases, including 10 cases died from different reasons. The incidence of MACCE in high PLR group was significantly higher than that in low PLR group (27.08% (13/48) vs. 11.28% (15/133), P＝0.009). Survival analysis showed that the all-cause mortality and the events free survival in high PLR group was significantly higher than that in low PLR group (P＝0.003). COX proportional hazard regression analysis showed that high PLR was an independent risk factor for MACCE after myocardial infarction (HR＝2.6,5%CI＝1.794, P＝0.035). Conclusion PLR is an independent and valuable index for predicting the occurrence of MACCE after direct PCI in patients with STEMI.