Aim To investigate the serum levels of thrombin-antithrombin complex(TAT),tissue type plas-minogen activator-inhibitor complex(t-PAIC)and thrombomodulin(TM)in patients with intracranial atherosclerotic steno-sis(ICAS),and their correlations with the degree of stenosis.Methods A total of 196 ICAS patients(ICAS group)who underwent treatment in Cangzhou People's Hospital from January 2021 to February 2023 were enrolled as research sub-jects.Based on the degree of vascular stenosis,they were separated into three groups:mild group(n=78),moderate group(n.=64),and severe group(n=54).A group of 196 healthy outpatient with similar clinical basic data to ICAS patients was selected as controls.The serum levels of TAT,t-PAIC,and TM in each group were compared;Spearman method was applied to analyze the correlation between serum levels of TAT,t-PAIC,TM and stenosis severity in ICAS pa-tients;Multivariate Logistic regression was applied to analyze the influencing factors of severe stenosis in ICAS patients;ROC curve was applied to analyze the predictive value of serum TAT,t-PAIC,TM and total cholesterol(TC)levels for se-vere stenosis in ICAS patients.Results Compared with the control group,the serum levels of TAT,t-PAIC,and TM were significantly increased in the ICAS group(P＜0.05);the levels of serum TAT,t-PAIC,TM,and TC in the mild,moderate,and severe groups increased accordingly(P＜0.05).Spearman analysis showed that the serum levels of TAT,t-PAIC,and TM in ICAS patients were positively correlated with the degree of stenosis(r=0.574,0.695,0.628;all P＜0.05).Multivariate Logistic regression analysis showed that TAT,t-PAIC,TM,and TC were independent risk factors for severe stenosis in ICAS patients(P＜0.05).The ROC curve showed that the AUC of severe stenosis in ICAS patients predicted by combination of TAT,t-PAIC,TM,and TC was 0.927,with a sensitivity of 83.33％and a specificity of 86.62％,which was superior to the independent prediction of TAT,t-PAIC,TM and TC(Zcombined detection-TAT=4.617,Zcombined deteetion-t-PAIC=4.024,Zcombined detection-TM=4.004,Zcombined detection-TC=7.078,all P=0.000).Conclusion The ser-um levels of TAT,t-PAIC,and TM in the ICAS group were significantly increased,and were positively correlated with the severity of stenosis.The combination of the three and TC has a high predictive value for the occurrence of severe stenosis in ICAS patients.