Abstract: Objective: To explore the correlation between arterial stiffness index (ASI) and coronary heart disease and its severity. Methods: A total of 535 patients suspected or diagnosed as coronary heart disease (CHD) were included and divided into control group (without obvious coronary artery disease),single-vessel disease group,and multi-vessel disease group (with ≥2 vessel disease branches) based on the results of coronary angiography.According to the results of coronary angiography,myocardial enzyme spectrum,electrocardiogram,echocardiography and clinical manifestations,these patients were divided into control group,stable angina (SA) group,unstable angina (UA) group and acute myocardial infarction (AMI) group.The general information and relevant laboratory indicators of all study subjects were collected,and the ASI levels were measured using an arterial hardness tester.The differences in ASI levels and related indicators were compared in these groups,and the receiver operating characteristic(ROC) curve was used to analyze ASI value in the diagnosis and assessment of CHD severity. Results: With the increase of coronary artery lesions numbers,ASI was increased (P<0.01),the ASI values in SA,UA and AMI groups were all higher than those in control group (P<0.05 to P<0.01),and the ASI values in UA and AMI groups were higher than those in SA group (P<0.01).However,there was no statistical difference of ASI values between the UA and AMI groups (P>0.05).The ROC curve analysis results showed that the sensitivity and specificity of ASI in diagnosing CHD were 69.7% and 85.4%,respectively.The sensitivity and specificity for evaluating the severity of CHD were 74.6% and 58.3%,respectively. Conclusions: ASI has a certain reference value for assisting in the diagnosis of CHD and evaluating its severity.