Abstract: With the continuous increase in mining depth and mining and excavtion intensity in Dananhu No.1 Mine, the spontaneous combustion problem of protection coal pillars in roadways has become increasingly prominent, and the demand for accurate early warning of fire disasters in early stage has become more urgent. Thus, based on the pressure-bearing coal body oxidation and heating theory, a pressure-bearing coal body programmed heating experimental device is utilized to systematically simulate the spontaneous combustion and oxidation processes of broken coal samples and intact coal pillars under different pressure-bearing states. The laws of single gas indicators (CO, C₂H₄) and composite gas indicators (△CO/△O₂) changing with coal temperature are deeply explored. The research results show that the initial appearance temperature of CO for both types of coal samples is 30 ℃, but there are differences in the C₂H₄ occurrence temperature and the △CO/△O₂ ratio. Based on the research results, a three-level classification early warning technology for coal pillar spontaneous combustion is proposed, which divides the spontaneous combustion process into three stages: low temperature oxidation (30-90 ℃), rapid oxidation (90-100 ℃), and severe oxidation (>100 ℃), CO occurrence, C₂H₄ occurrence, and △CO/△O₂≥0.2 are set as early warning indicators for each stage, providing specific methods and theoretical support for the accurate early warning of coal pillar spontaneous combustion fire disasters under deep mining conditions.