<p>Because of material ablation, manufacturing tolerances, or unforeseen issues such as insulation tile detachment, the surfaces of hypersonic vehicles are prone to developing concave cavity structures. These imperfections can induce boundary layer transition, significantly affecting the dynamic characteristics of the vehicles. In this study, coupled calculations of transition and forced oscillation are performed to investigate the impact of different cavity positions on the dynamic characteristics of a hypersonic blunt cone. The underlying mechanisms are clarified through a decomposition of pitching moments. Results indicate that, compared with a smooth model, cavity-induced transition reduces the dynamic stability of hypersonic vehicles. When the cavity normal is aligned with the direction of forced oscillation, the pitching moment coefficient amplitude in the pitching plane reaches its maximum, resulting in a pronounced decrease in dynamic stability. The decomposition of pitching moments further reveals that the increase in wall pressure caused by the cavity is the fundamental reason for the change in the vehicle’s dynamic characteristics.</p>