Abstract: In order to explore the influence of coal metamorphic degree on the characteristics of coal spontaneous combustion and the shortest spontaneous combustion period，five kinds of coal samples with different metamorphic degrees are selected to carry out industrial analysis，elemental analysis，tempera⁃ ture programmed oxidation and differential scanning calorimetry (DSC) test. The apparent activation energy of oxidation is calculated by water correction Kissinger method，and the prediction model of the shortest spontaneous combustion period is constructed by multiple linear regression. The results show that with the decrease of coal metamorphism，the moisture and volatile content of coal increase，the endothermic char⁃ acteristics of DSC increase，the zero point of heat flow advances，and the apparent activation energy of oxi⁃ dation decreases as a whole. The fixed carbon and oxygen contents are significantly positively correlated with the apparent activation energy，and the correlation coefficients are 0.942 and 0.901，respectively. The relative error of the measured verification of the model is not more than 4.4%，and the prediction accuracy is high. The average error of leave-one-out cross-validation is 12.5%，indicating that the empirical model has the ability to estimate quickly on site，but the generalization accuracy still needs to be optimized by ex⁃ panding the sample. Studies have confirmed that the degree of coal metamorphism dominates the spontane⁃ ous combustion tendency and ignition timing of coal by regulating the chemical composition and oxidation reaction energy barrier of coal. The prediction formula based on conventional detection indicators can quickly estimate the shortest spontaneous combustion period of coal seam at low cost，which is suitable for preliminary prediction of mine spontaneous combustion risk.

Key words: coal spontaneous combustion, differential scanning calorimetry, shortest spontaneous combustion period, water correction Kissinger method, CO release law