Abstract: In view of the heat transfer problems of gap flows near the shock-wave interference region of hypersonic vehicles, a two-dimensional model of the shock generator and gap was established. By using CFD technology, the internal flow heat transfer characteristics with shock waves in the front, middle and back of the gap were studied. The results showed that compared to the flow fields without shock wave, the vortex structure of the flow inside the gap changes obviously when the shock wave acts on the front and middle of the gap, resulting in a sharp increase in the flow intensity and heat inside the gap. However, when the shock wave acts on the rear part of the gap, the vortex structure inside the gap does not change significantly, and the far-end wall heat flux near the gap lip decreases locally, which is beneficial to the shape protection of the thermal protection structure. The results clearly indicated that it is necessary to avoid the position where shock wave acts on the front and middle part of gap in structural thermal protection design.