Abstract: Spontaneous combustion process of lignite is studied systematically to analyze its self-heating characteristics. The effect of coal quality, particle size, air flow rate and moisture content on the self-heating characteristics is researched by combining with gaseous oxidation products. The characteristic temperature such as cross point temperature (CPT) and combustion temperature (CT1, CT2) reflects the self-heating characteristics of lignite in the process of spontaneous combustion. The results show that characteristic temperature of smaller quality coal sample tends to be high. The small particle size shortens the time of spontaneous combustion and accelerates CO₂ generation rate. After CT1, coal temperature and CO₂ generation rate goes up with the increase of gas flow rate. With the increase of moisture content, spontaneous combustion time of lignite with different water content is different, which may be "pore collapse" occuring at the drying process.