Abstract: The internal environment of large mined-out areas formed by the connection of old and new mined-out regions is complex, with severe air leakage, which easily triggers the oxidation and temperature rise of residual coal, increasing the risk of spontaneous combustion in the mined-out areas. Using the 6315 working face of Tangkou Mine as a prototype, a calculation area for the large connected mined-out area was constructed, and a multiphysics coupling numerical model was established. By using dynamic mesh technology, the dynamic evolution process of the entire area after the advancement of the working face was further realized, and the air leakage patterns in the large-area connected goaf were analyzed. The results show that the air leakage flow along the horizontal center line perpendicular to the working face wall exhibits an asymmetric distribution, with the airflow returning to the working face prematurely. The oxidation zone in the 6315 working face mined-out area appears as a curved belt, while in the old mined-out area with severe air leakage, it appears as a strip. As the working face advances, the “three zones” also move forward and their range gradually increases.