Abstract: In the process of coal mining, coal spontaneous combustion seriously threatens mine safety. As an efficient fire extinguishing medium, it is of great significance to explore the cooling effect of liquid CO₂ (LCO₂) after it injected into high temperature coal. In order to master the cooling law of LCO₂ pressure injection into high temperature coal body, the temperature change law of LCO₂ pressure injection into high temperature coal body was analyzed by experiment on the experimental platform designed and built by ourselves. The 1∶1 numerical model was established by using the numerical software COMSOL. Based on the CO₂ gas seepage control equation, component transport equation, energy conservation equation and phase equation, the numerical model of LCO₂ cooling coupling in high temperature coal was established, and the cooling process of LCO₂ was simulated. Comparing the experimental results with the numerical simulation results, the accuracy of the numerical model is verified, and the effects of LCO₂ pressure injection volume, release nozzle diameter and the longitudinal distance of the release outlet from the central axis on the cooling effect are analyzed. The results show that there is a negative exponential function correlation between the cooling amount of 1^# high temperature point and the LCO₂ pressure injection volume, a logarithmic function correlation with the release nozzle diameter, and a linear correlation with the longitudinal distance of the center axis of the release outlet. The determination coefficients are 0.997, 0.999 and 0.989, respectively. With the increase of injection volume, the area where the cooling area is less than 20 ℃ gradually increases. When 30 L LCO₂ is injected, the high temperature points of 1^# and 2^# rapidly cool down. Continuous to inject LCO₂, the temperature at the high temperature point decreases slowly. With the increase of the release nozzle diameter, the cooling amount of 1^# high temperature point increases and the area below 20 ℃ first expands rapidly, and the area growth becomes slow after expanding to 0.346 m². With the increase of the longitudinal distance between the release outlet and central axis, the region below 20 ℃ moves toward the release outlet. As the offset distance increases, the area cooled below 20 ℃ decreases, and the cooling amount at 1^# high-temperature point also decreases.