Abstract: Low-rank coal is very complex in composition and differs in the proximate analysis, which significantly affects the ignition. In order to further explore the ignition tendency of low rank coal, the thermal behavior of BRXL and YJL low rank coal is systematically studied in stages from the perspective of macro and micro combination. Among them, the primary and secondary stage results can infer the key stage affecting the ignition. In this stage, the two kinds of coal have concentrated reaction and exothermic heat, but the heat storage process of BRXL is earlier than that of YJL. In addition, the reaction gas release process of the two kinds of coal appeared abnormal. Combined with the pore size evolution characteristics, it can be found that BRXL and YJL are affected by micropores（＜２ ｎｍ） and 2-10 nm mesoporous, respectively. Because of the uniform distribution of the original pore size, BRXL ensures the smooth reaction and smooth gas release, so the rapid accumulation of reaction heat leads to BRXL showing a stronger ignition tendency than YJL.