The oxidation of coal at room temperature provides the initial heat source for spontaneous coal combustion, exploring the active substances in coal that can oxidize with oxygen at room temperature is a complex problem. Previous thermal decomposition experiments have found that coal contains active sites of free radicals that can exist stably in inert gases and oxidize with oxygen at room temperature. So it is speculated that there may also be native active sites that are forced to be stored under inert media in coal. To explore the native active sites of coal, vacuum drying technology is applied so that the water in the original coal can reach the boiling point under the low-temperature environment of negative vacuum pressure to complete the removal of water and gas. At the same time, the cyclic oxidation online monitoring technology is used to design and implement the room temperature oxidation experiment of the desorbed coal samples under different experimental conditions, and analyze the reaction mechanism combined with the corresponding low-temperature nitrogen adsorption, XPS, ESR experiments. After vacuum desorbed, oxidation experiments under cyclic conditions show that a large number of gaseous oxidation products such as CO and CO₂ will be formed in coal in the process of oxidation at room temperature, and the gases appear and accumulate soon after oxygen is introduced, which proves that coal oxidation can occur at room temperature. The room temperature oxidation experiment after the desorption of raw coal indicates that there are a large number of active sites affected by water-gas masking in the original coal, and they are unable to undergo the oxidation exothermic processes, while the coal after the desorption of water and gas under negative pressure exposes massive free radical active sites and forms a channel conducive to oxygen transport and reaction, which rapidly occur oxidation exothermic phenomenon and lead to the rise of coal temperature. Therefore, the active structure leading to the self-heating of the raw coal was found, and the experiments extended the view of room temperature oxidation of the active sites from the particular case state to the general state.