Objective To investigate the relationship between plasminogen activator inhibitor-1(PAI-1)and mean platelet volume/platelet count ratio(MPV/PLT)with infarct size and cerebral artery stenosis in pa-tients with cerebral infarction.Methods A total of 136 patients with cerebral infarction admitted the hospital from January 2022 to January 2024 were selected as observation group,and another 136 healthy individuals who underwent health check-ups were concurrently selected as control group.136 patients with cerebral in-farction were divided into small infarction group,medium infarction group,and large infarction group based on the infarct size.They were also divided into mild stenosis group,moderate stenosis group,severe stenosis group,and occlusion group based on cerebral artery stenosis degree.PAI-1 level was determined using enzyme-linked immunosorbent assay.Mean platelet volume and platelet count ratio were analyzed by fully automated hematology analyzer,and MPV/PLT was calculated.PAI-1 and MPV/PLT were compared among groups.Then receiver operating characteristic(ROC)curve was plotted to evaluate the value of PAI-1 and MPV/PLT in the diagnosis of cerebral infraction,and the correlation of PAI-1 and MPV/PLT with infarct size and cere-bral artery stenosis degree in patients with cerebral infarction was verified using Spearman correlation analy-sis.Results PAI-1 and MPV/PLT were elevated in observation group compared to control group(P＜0.05).ROC curve analysis yielded that the area under the curve(AUC)of single detection of PAI-1 and MPV/PLT in the diagnosis of cerebral infarction was 0.820(95％CI:0.768-0.873)and 0.754(95％CI:0.695-0.814),while the combined detection of the two reached an AUC of 0.896(95％CI:0.853-0.938).The ser-um PAI-1 level and MPV/PLT in the large infarction group were higher than those in the medium infarction group and small infarction group(P＜0.05),and the levels of the above indicators in the medium infarction group were higher than those in the small infarction group(P＜0.05).The serum PAI-1 level and MPV/PLT in the occlusion group were higher than those in the severe stenosis group,moderate stenosis group and mild stenosis group(P＜0.05),the levels of the above indicators in the severe stenosis group were higher than those in the moderate stenosis group and mild stenosis group(P＜0.05),and the levels of the above indicators in the moderate stenosis group were higher than those in the mild stenosis group(P＜0.05).Spearman corre-lation analysis yielded that PAI-1 and MPV/PLT were positively correlated with infarct size and cerebral ar-tery degree stenosis in patients with cerebral infarction(P＜0.05).Conclusion Patients with cerebral infarc-tion have abnormally elevated PAI-1 and MPV/PLT,and the two indicators are closely correlated with infarct size and cerebral artery stenosis,which have significant potential value in early diagnosis,treatment,and dis-ease assessment of diseases.