To investigate the inhibitory effect of calcium carbonate on methane explosion in the presence of coal dust, experiments and numerical simulations were applied in this study. The inhibitory performance of calcium carbonate under various particle sizes and concentrations was analyzed, providing a theoretical basis for safety protection in high-risk environments, such as coal mines. By using a self-developed 9.6-meter-square straight pipe, the experiments were conducted with Calcium carbonate, whose particle sizes ranged from 6.5 to 74 micrometers, and the concentration levels were maintained within the optimal range of 100 to 200 g/m³. Based on this, the optimal particle size and concentration of calcium carbonate were determined by analyzing the pressure changes during the explosion process. The experimental findings reveal that the explosion process can be divided into four stages: initial methane combustion, subsequent methane combustion involving coal dust, calcium carbonate decomposition, and a final inhibition stage. Meanwhile, the calcium carbonate reduces oxygen concentration. It absorbs heat through thermal decomposition reactions, which slows down the combustion reaction rate and establishes local thermal equilibrium, thereby suppressing the propagation of the explosion. The calcium carbonate achieves optimal explosion suppression performance with a maximum pressure reduction rate of 46.7% at specific parameters: a calcium carbonate of 150 g/m³ combined with a particle size of 23 micrometers. Additionally, numerical simulations were employed to verify the experimental results, which demonstrate that the pressure change trends are consistent with the experimental results, with a relative error of less than 15%. As an effective explosion inhibitor, calcium carbonate demonstrates significant inhibitory effects on methane explosions in the presence of coal dust under specific particle size and concentration conditions. This study provides experimental and theoretical support for the application of calcium carbonate in industrial explosion protection.