Sequential graft was used frequently in clinical studies. In this study, the hemodynamic effect of one kind of sequential graft in two different conditions of the lesion was discussed and some recommendations on the surgical procedures were made. A patient-specific three-dimensional (3D) model of left anterior descending artery (LAD) was reconstructed. A moderate stenosis exist in the trunk of LAD between the first and the second diagonal branch (D1 and D2). Another 3D model without stenosis was also reconstructed based on the patient-specific model. Sequential graft and single graft were applied on these two 3D model. Thus four 3D models were built so that the hemodynamic effect of sequential graft can be discussed. The zero-dimensional (0D)/3D coupling method was used to perform the numerical simulation by coupling the 3D artery model with a 0D lumped parameter model of the cardiovascular system. The flow rates in the branches of LAD and the graft flow were calculated and illustrated in this paper. The wall shear stress (WSS) and oscillatory shear index (OSI) were also calculated and depicted. If the native LAD is stenosis, sequential graft should be applied for the short-term outcomes. Moreover, the long-term patency of the sequential graft applied on the stenosis LAD is good. The long-term patency of the single graft was bad. But the short-term outcomes are almost the same when LAD is not stenosis. If no stenosis exist in the native LAD, a graft with smaller diameter should be applied to improve the long-term patency.