Objective To investigate the pathogenesis of type-B aortic dissection by using morphological analysis and computational fluid dynamics (CFD) method, so as to provide evidence for the effective prediction of type-B aortic dissection. Methods Six primary type-B dissection cases scanned by CT (dissection group) and six normal cases applied to black-blood MRI (control group) were included in this study and patient-specific three-dimensional (3D) models of aorta were established through image segmentation and 3D reconstruction. The pre-type-B dissection aortas were constructed by applying the scaling algorithm to shrink the dissection and then compared with subjects in control group. The differences between morphological parameters and hemodynamic parameters of the two groups were compared. Results Compared with the normal cases, the area of the descending aorta increased dramatically in dissection group ［(892.03±263.78) mm2 vs (523.67±64.10) mm2, P=0.036］. A significant decrease in angle of the left subclavian artery occurred (66.62°±20.11° vs 100.40°±15.35°, P=0.036). The tortuosity of the aorta also had an obvious increase (0.37°±0.07° vs 0.21°±0.51°, P=0.011). The time-averaged wall shear stress (TAWSS) in dissection group was obviously higher than that in control group; the flow in the dissection region was vortex flow at low speed and the oscillating shear index (OSI) was higher. Conclusions The results of this study can be used to provide guidance for the early diagnosis and treatment of type-B aortic dissection.