Objective Exploring the relationship between the Platelet-to-Lymphocyte Ratio (PLR), Neutrophil-to-Lymphocyte Ratio (NLR), Global Registry of Acute Coronary Events (GRACE) score in peripheral blood before Percutaneous Coronary Intervention (PCI) and Major Adverse Cardiovascular Events (MACE) after the procedure in patients with acute ST-segment elevation myocardial infarction (STEMI). Methods A retrospective analysis was conducted on the data of 216 STEMI patients admitted to Hebei General Hospital from July 2021 to September 2022, with a follow-up period of one year. Basic information, GRACE scores, and MACE data were collected. Patients were divided into the MACE group (77 cases) and the non-MACE group (139 cases) based on whether they experienced MACE. Subsequently, indicators with statistically significant differences between the two groups were further included in a multivariate logistic regression analysis to identify independent risk factors for MACE within one year after PCI in STEMI patients. Additionally, the Receiver Operating Characteristic (ROC) curve was used to evaluate the efficacy of PLR, NLR, and GRACE scores in predicting MACE events. Results The PLR, NLR, age, BNP, proportion of Killip class ≥Ⅱ, and GRACE score were significantly higher in the MACE group than in the non-MACE group, while Left Ventricular Ejection Fraction (LVEF), Triglycerides (TG), Systolic Blood Pressure (SBP), and Body Mass Index (BMI) were significantly lower in the MACE group, with statistically significant differences (P＜0.05). Multivariate logistic regression analysis showed that PLR and GRACE score were confirmed as independent risk indicators for MACE within one year after PCI in STEMI patients (P＜0.05), while NLR was not an independent risk factor. Subgroup analysis of GRACE risk stratification (i.e., low-risk, medium-risk, high-risk groups) confirmed that NLR was elevated in high-risk group patients; grouping based on the cutoff values of NLR and PLR calculated by the ROC curve (i.e., PLR-NLR 0, 1, 2 groups) combined with GRACE risk stratification grouping results showed that the number of patients in the PLR-NLR 2 group increased in the medium-risk and high-risk groups compared to the 0 and 1 groups, with statistically significant differences. ROC analysis results showed that the AUC for PLR, NLR, and GRACE score alone in predicting MACE was 0.686 (95% CI: 0.611-0.761), 0.702 (95% CI: 0.635-0.776), and 0.782 (95%CI: 0.712-0.853), respectively, and the AUC for the combined prediction of the three was 0.802 (95% CI: 0.738-0.866). Conclusion PLR and GRACE score are independent risk factors for MACE within one year after PCI in STEMI patients, and high NLR and high PLR are associated with higher GRACE scores in STEMI patients; the combination of PLR, NLR, and GRACE score has predictive value for the occurrence of MACE events within one year after PCI in STEMI patients