Abstract: In order to investigate the inhibition behavior of the two composite inhibitors formed by the combination of carbon/oxygen radical scavenger (DBHA/BHT) and MgCl₂ on coal spontaneous combustion, thermal analysis (TG-DSC), inhibition performance test and Fourier infrared analysis(FTIR) experiments were used to study spontaneous combustion characteristic of coal samples before and after inhibition treatment. The results show that the release amount of CO from coal samples treated by the composite inhibitor decreases, and the CPT and the inhibition rate increase significantly; the composite inhibitor can reduce the content of active components such as hydroxyl, carbonyl and aliphatic -C-H content. Before 80℃, MgCl₂ play a major role in physical inhibition, and BHT and DBHA form associated hydrogen bonds with water molecules to play a cooperative role in inhibition; from 80℃ to 120℃, BHT combines with oxygen-containing active radicals in coal to inhibit the adsorption of coal and oxygen and the formation of CO compounds, the synergistic inhibition effect is superior to DBHA composite inhibitor; after 120℃, the inhibition rate of coal samples treated with DBHA composite inhibitors is above 70%, the ability to capture free radicals is stronger and its stability is higher than BHT.