Objective To study the effect of the morphologic characteristics of Modular Inner Branched Stent Graft (MIBSG) on the hemodynamics of postoperative aortic arch by numerical simulation, aiming to provide certain theoretical guidance for the determination of modular embedded stent parameters, surgical programming, postoperative effectiveness and safety assessment. Methods CAD models of MIBSG with various branch angle and diameter were established. Then, the fluid – structure interaction (FSI) between blood – MIBSG is solved numerically. Based on the numerical results, the effects of kinds of parameters, i.e., morphological parameters such as the angle between the branch stent, the diameters of stents, and hemodynamic quantities such as velocity, von Mises stress, displacement of the inner wall and outlet flow rate ratio on the hemodynamic characteristics are investigated. Results The results show that as the angle between the branch stent and the aortic arch stent increased, the blood flow within the branch decreased, but the stress and displacement increased. Different from the change of angle, the change of the diameter of the branching stent has more influence on the hemodynamic parameters. With the decrease of the diameter of the stent, the blood flow perfusion would decrease significantly, but the stress and displacement of the branching stent show a different tendency, that is, they increase first, followed by decrease. Conclusions The idealized MIBSG stent model is a useful tool to investigate various parameters’ effect on the hemodynamic characteristics of blood flow, for that the idealized model is fully parameterized and its geometric characteristics is tunable, so the effect of a parameter on the hemodynamic characteristics should been investigated in detail. This is an advantage of idealized parameterized MIBSG compared to the three-dimensional reconstructed stent model based on CT images. Based on this model, the results of this study are of great significance to the establishment of a complete personalized diagnosis and treatment integration scheme, such as modular inline stent preoperative evaluation, surgical planning, in-service navigation and postoperative risk prediction.