Coronary arteries are responsible for supplying oxygen-rich blood to the heart muscle, and their obstruction due to atherosclerosis can lead to cardiac arrest. One of the common treatments for this obstruction is coronary artery bypass grafting (CABG), in which grafts such as the radial artery, internal thoracic artery, and saphenous vein are used to create an alternative pathway for blood flow. The optimal geometric design of grafts, particularly their length, can play a significant role in improving graft durability and reducing postoperative complications. In this study, the effect of graft length on mechanical parameters influencing graft integrity was investigated. To this end, 12 geometric models with different graft lengths (dimensionless lengths of 1.03, 1.05, 1.12, and 1.2) were designed for each of the three commonly used graft types, and finite element analysis was performed in a dry state without considering fluid flow, focusing solely on the coronary and graft walls. Furthermore, to better simulate physiological conditions, the motion of the host coronary wall caused by the cardiac cycle was applied to the coronary artery. The results showed that, in the case of a moving coronary artery, an increase in graft length led to a reduction in von Mises stress and strain energy density within the graft, thereby lowering the likelihood of mechanical failure of the graft wall. In contrast, for a fixed coronary artery, no consistent relationship was observed between graft length and the mechanical parameters. Moreover, comparison of stress values with the ultimate tensile strength of the graft tissues revealed that the use of radial artery and saphenous vein grafts in a stretched configuration (length 1.03) significantly increases the risk of graft rupture.