In order to systematically evaluate the safety risks caused by coal spontaneous combustion, this study selected representative metamorphic coal samples (non-caking coal, weakly caking coal and lean coal) as the research object, and systematically studied their spontaneous combustion characteristics by using the programmed temperature experiment method. Through real-time monitoring of key parameters such as gas yield, oxygen consumption rate and exothermic intensity, combined with the analysis of apparent activation energy, the thermochemical evolution law of coal samples in the process of low temperature oxidation was deeply revealed. On this basis, the temperature dependence of the critical condition parameters of coal spontaneous combustion-the minimum floating coal thickness (hmin), lower limit oxygen volume fraction (Cmin) and the upper limit air leakage intensity (Qmax) was studied. The results show that the low metamorphic coal has higher oxygen consumption rate, and its oxidation process presents the typical characteristics of ' stable-slow increase-rapid increase-slow down '. Before 160 °C, the low metamorphic coal shows lower activation energy and stronger heat release capacity, showing higher spontaneous combustion tendency; the evolution of limit parameters shows that hmin and Cmin are positively correlated with the degree of coal metamorphism, while Qmax is opposite. This study provides a theoretical basis and data support for coal mine fire risk assessment and accurate early warning.