Abstract： Objective To investigate the correlation study between the morphology of intraluminal thrombus in the abdominal aortic aneurysm(AAA)and type Ⅱ endoleak after endovascular aneurysm repair(EVAR).Method The clinical data and imaging data(computed tomography angiography imaging data)of 182 AAA patients who received EVAR treatment at Binzhou Second People's Hospital and Provincial Hospital Affiliated to Shandong First Medical University from January 2018 to June 2022 were collected.According to whether type Ⅱ endoleak occurred during the follow-up period,the patients were divided into type Ⅱ endoleak group(n=44)and control group(n=138).The clinical characteristics,blood indicators,and computed tomography angiography(CTA)imaging characteristics of two groups of patients were compared,the influencing factors of type Ⅱ internal endoleak after EVAR surgery was screened,the prediction model was established and draw nomogram was drawn,and the accuracy of the predictive model was verified by drawing the calibration curve,receiver operating characteristic(ROC)curve,and clinical decision curve of the model.Result The differences in hypertension history,smoking history,maximum cross-sectional thrombus thickness,maximum cross-sectional thrombus area,thrombus volume,maximum tumor diameter,and number of lumbar arteries between the two groups of patients were statistically significant(P<0.05).The results of multiple factor analysis showed that thick maximum cross-sectional thrombus thickness,large maximum cross-sectional thrombus area,and large thrombus volume were all protective factors for type Ⅱ internal endoleak after EVAR surgery,while the large number of lumbar arteries was a risk factor for type Ⅱ internal endoleak after EVAR surgery(P<0.05).The area under the ROC curve of the model is 0.901.The calibration curve shows that the predicted curve of the model overlaps well with the expected curve.The clinical decision curve shows that if the cutoff value was between 4%and 98%,the clinical effectiveness of the model was good.Conclusion The maximum cross-sectional thrombus thickness,maximum cross-sectional thrombus area,thrombus volume,and the number of lumbar arteries are influencing factors of type Ⅱ endoleak.The predictive model established in this study has high accuracy,which can be used to predict the incidence of type Ⅱ endoleak after endovascular aneurysm repair.