Objective To explore the preoperative diagnostic value of multi slice spiral CT post-process-ing technology for intralobar pulmonary sequestration.Methods A total of 54 patients with abnormal arterial blood supply admitted to the First Affiliated Hospital of Henan University of Traditional Chinese Medicine were included retrospectively as the study subjects,including 43 patients with intralobar pulmonary isolation(study group)and 11 patients with normal inferior pulmonary lobe(control group).All patients underwent preoperative multi-slice spiral CT chest plain scan and enhanced scan.Four CT post-processing techniques(MPR,CPR,MIP,and VR)were used to reconstruct the images.The location of abnormal body artery blood supply,other changes in the lungs,and characteristics of blood supply arteries and reflux veins in two groups of patients were analyzed and recorded.Kappa consistency test was used to evaluate the consistency of the re-sults of two physicians' readings.Spearman correlation test was used to evaluate the correlation between the diagnostic results of four post-processing techniques.ROC curve and Delong test were used to evaluate their independent and combined diagnostic efficacy for intrapulmonary sequestration.Results The Kappa test con-sistency coefficient of the two physicians' reading results was r=0.872,P＜0.05.The Spearman test correla-tion coefficients between the diagnostic results of the four post-processing techniques were 0.876(MPR and CPR),0.849(MPR and MIP),0.876(MPR and VR),0.738(CPR and MIP),1.000(CPR and VR),and 0.738(MIP and VR),respectively,with P＜0.05.The AUC values for independent diagnosis of MPR,CPR,MIP,and VR were 0.66,0.58,0.70,and 0.53,respectively.The sensitivities were 95.35％,69.77％,76.74％,and 69.77％,respectively.The specificities were 36.36％,45.45％,63.64％,and 36.36％,respectively.The Youden indexes were 0.32,0.15,0.40,and 0.06,respectively.The accuracies were 88.37％,83.72％,90.70％and 83.72％,respectively.The AUC value,sensitivity,specificity,Youden index,and accuracy of joint diagno-sis were 0.78,83.72％,72.73％,0.56,and 95.35％,respectively.Conclusion The combined application of CTA,MPR,VR,and MIP post-processing techniques has the best diagnostic efficacy for intralayer pulmonary sequestration and can be used for precise preoperative evaluation in clinical practice.