Blunt aortic injury in vehicle crash accident may occur at any moment of the cardiac cycle. However, the influence of hemodynamic characteristics at different physiological stages on the aortic mechanical response under seatbelt restraint loading remains insufficiently understood. This study developed a physiologically characteristics fluid-structure interaction (FSI) model based on a heart-aorta finite element system and validated its hemodynamic simulation reliability. On this basis, a stepwise modeling strategy was employed to establish a thorax-enclosed visceral organs FSI model under seatbelt restraint loading. Numerical simulation analysis of different physiological stages of the heart during systole (early, mid, and late) was achieved by changing the left ventricular motion displacement and aortic outlet pressure boundary conditions. The results indicated that during the rapid ejection phase (mid-systole), there was a higher risk of aortic injury under seatbelt restraint loading. During the rapid ejection phase, the aortic arch region exhibited a peak strain of 0.148 at 0.12 s, representing 9.4% and 6.1% increases compared to early-systole and late-systole phases, respectively. The peak blood pressure at the outlet of the descending aorta reached 137.33 mmHg at 0.08 s, which was 14.7% and 9.6% higher than that in the early and late systole, respectively. The established thorax-viscera integrated FSI model under seatbelt restraint loading demonstrated the capability to simulate hemodynamic responses of the aorta under complex loading conditions, providing a technical reference for analyzing physiological state-dependent aortic injury mechanisms.