Background and aims: Sequential grafting is one of the common coronary artery bypass grafting (CABG) surgery. But the influence of the sequential grafting position on hemodynamics and the graft patency is still unclear. Materials and methods: The zero-dimensional/three-dimensional (0D/3D) coupling method was used to finalize the multi-scale simulation of two different sequential grafting models. First, a patient-specific 3D model was reconstructed based on coronary computed tomography angiography (CCTA) images. Two different sequential grafts were implemented on this patient-specific 3D model by using virtual surgery. Thus, two different postoperative 3D models were built. Then, a lumped parameter model (LPM; 0D) was built based on the patient physiological data to simulate the cardiovascular system. Finally, the 0D/3D coupling method was used to perform the numerical simulation by coupling a 0D LPM of the cardiovascular system and the patient-specific 3D models. Moreover, the long-term patency of these two different sequential grafts was discussed in this paper. Results: The coronary flow rate and the graft flow were calculated and illustrated. The instantaneous wave-free ratio (iFR) were calculated. Postoperative iFR values increase to over 0.90 for both sequential grafts. Some hemodynamics parameters were also illustrated, such as wall shear stress (WSS), oscillatory shear index (OSI). The area of low WSS in Model 1 was much less than that in Model 2. Two regions of high OSI exist in Model 2, while only one in Model 1. Conclusions: No significant differences exist on the short-term outcomes of two models. But the long-term patency of Model 2 was worse. The Model 1 may enhance long-term patency of grafting and should be priority when the sequential grafting need to be carried out.