Abstract: To study the influence of MgCl₂ on initial oxidation and secondary oxidation of coal, temperature-programming method is used to study different characteristics of initial oxidation and secondary oxidation of long flame coal. The results show that CO, CO₂ production and oxygen consumption rate of initial oxidation of coal samples without MgCl₂ inhibitor treatment are higher than that of secondary oxidation; when the coal temperature is below 110 ℃, CO, CO₂ production and oxygen consumption rate of initial oxidation of coal samples after MgCl₂ inhibitor treatment are less than that of secondary oxidation; when coal temperature is at 110 ℃ to 140 ℃, secondary oxidation is more complete than initial oxidation.