Abstract: In order to explore the inhibiting effect of sodium phosphate inhibitors on spontaneous combustion oxidation of coal, taking gas coal as the experimental coal sample, two types of sodium phosphate (NaH₂PO₄ and Na₃PO₄) were selected to prepare inhibitors. By synchronous thermal analysis experiment and programmed temperature-rise oxidation experiment, the effects of sodium phosphate on the characteristics of thermal weight loss, thermal release and gas phase during coal spontaneous combustion were analyzed.The results show that Na₃PO₄ no longer has resistance when the spontaneous combustion of coal reaches the pyrolysis temperature; NaH₂PO₄ significantly improves the critical temperature, dry crack temperature and ignition temperature of coal spontaneous combustion, in addition, NaH₂PO₄ not only effectively increases the initial exothermic temperature and maximum exothermic temperature, but also reduces the maximum exothermic power and heat release of coal spontaneous combustion; NaH₂PO₄ improves the initial generation temperature of CO, CO₂ and hydrocarbon gases during coal spontaneous combustion and weakens its release intensity, its resistance rate reaches 65.4%; compared with Na₃PO₄ inhibitor, NaH₂PO₄ inhibitor has better inhibiting effect and plays an inhibitory role in the whole process of coal spontaneous combustion.