Abstract: Leakage airflow in goafs is a key factor inducing the oxidation, self-heating, and spontaneous combustion of residual coal. Variations in leakage airflow velocity directly affect oxygen supply, heat accumulation, and gas migration, thereby determining the development intensity and spatial distribution of spontaneous combustion within the goaf. To reveal the influence of leakage airflow velocity on the oxidation behavior of residual coal, six groups of different leakage airflow velocities were tested using a programmed temperature-rise oxidation kinetics apparatus. The oxygen consumption rate, heat release intensity, and apparent activation energy of lignite from Puhe Coal Mine were systematically measured, and their variations with temperature were analyzed. Meanwhile, based on a 10 m × 5 m × 1 m physical similarity goaf model, 25 monitoring points were arranged under a constant intake airflow velocity of 0.52 m/s to analyze the spatial distribution characteristics of airflow velocity, temperature, and CO volume fraction inside the goaf and to investigate the influence of the non-uniform leakage airflow field on the coupled thermo-gas field. The results indicate that leakage airflow velocity has a significant impact on the oxygen consumption rate, heat release intensity, and apparent activation energy of coal. Comprehensive analysis of the six tested velocities shows that the oxidation and heat accumulation characteristics are most pronounced at 0.37 m/min; at 170 ℃, the oxygen consumption rate reaches 2.80 × 10⁻⁷ mol/(cm³·s), and the heat release intensity reaches 1.66 × 10⁻² J/(cm³·s). Physical similarity experiments show that when the intake airway velocity is 0.52 m/s, the initial high-temperature point appears near the face-adjacent area close to the intake corner, then gradually extends toward the return airway and migrates deeper into the goaf, eventually forming a relatively stable high-temperature zone with a local airflow velocity of 0.33 m/min. The CO volume fraction field exhibits a high degree of correspondence with the temperature field; regions of high CO volume fraction are mainly distributed around the high-temperature point and its downwind side, showing a synergistic spatial feature of heat source–CO enrichment. These findings reveal the key influence of leakage airflow velocity on the oxidation of residual coal and the development of spontaneous combustion in goafs from both oxidation kinetics and thermo-gas field evolution perspectives. The results provide scientific support for predicting, early warning, and preventing goaf fires in mining faces.