Abstract: Spraying inhibitors in the goaf can prevent and control coal spontaneous combustion. To investigate the effects of different halogen salt inhibitors and their mass fractions on the prevention and control of spontaneous combustion of residual coal in the goaf, the 51102 working face of Jintong Mining Co., Ltd. was taken as the research background (the mined coal seam is Class Ⅰ easy-to-spontaneous-combustion coal seam, and the coal dust is explosive, leading to a high risk of spontaneous combustion). The inhibition performance of inhibitors was analyzed through temperature-programmed experiments coupled with gas chromatography and thermogravimetric tests, and the optimal inhibitor type and spraying concentration were optimized. Furthermore, the inhibition mechanism of inhibitors on coal spontaneous combustion was revealed via molecular dynamics simulation. The results show that the inhibition efficiency of different inhibitors ranks as MgCl₂·6H₂O > CaCl₂·2H₂O > NaCl. The difference in inhibition performance is small at low temperatures but gradually increases with rising temperature. The inhibition performance of halogen salt inhibitors is positively correlated with their mass fractions; however, the growth rate of inhibition efficiency gradually decreases with increasing mass fraction. Considering both inhibition effect and economic benefit, MgCl₂·6H₂O with a mass fraction of 15 %-20 % is determined as the optimal inhibitor. The interaction energies of the three inhibitor systems follow the order of NaCl < CaCl₂ < MgCl₂, indicating that MgCl₂ exhibits the strongest adsorption capacity on the coal surface. For MgCl₂ systems with five mass fractions, an inhibition adsorption peak appears at approximately 30 Å (1 Å = 10⁻¹⁰ m). The inhibition adsorption peak is relatively high at a mass fraction of 15%-20%, and the mean square displacement and diffusion coefficient of MgCl₂ molecules in the system are small under this condition, demonstrating the strongest adsorption capacity of MgCl₂ on the coal surface. Based on the optimization results, a solution with a mass fraction of 15% MgCl₂·6H₂O solution was applied as the inhibitor for coal spontaneous combustion prevention in the goaf. The measured temperatures at monitoring points in the goaf stably remained below 60 ℃, showing an excellent inhibition effect.