Abstract: In order to study the combustion characteristics of low-order coal in high temperature oxidation process, the cone calorimeter was used to test the ignition time, heat release rate, total heat release, mass loss rate, total mass loss, CO release and other parameters of three low-order metamorphic coal samples. The combustion efficiency of each coal sample was calculated, and then the relationship between the metamorphic degree of coal samples and combustion characteristic parameters was analyzed. The experimental results show that the ignition time of coal samples increase with the deepening of metamorphism degree, the heat release rate and total heat release amount of coal samples increase with the deepening of metamorphism degree, and their peak heat release rates also increase, which are 48.27, 98.98 and 108.91 kW/m2, respectively. The mass loss rate and total mass loss of coal samples decrease with the deepening of metamorphism degree, and the peak value of mass loss rate also decreases, which are 0.052, 0.049 and 0.044 g/s respectively. The maximum CO release amount of coal samples increase with the deepening of metamorphism degree. In the early stage of combustion, the CO release amount of long-flame coal is larger than that of gas coal and 1/3 coking coal, but in the late stage of combustion, the CO release amount of long-flame coal is smaller than that of gas coal and 1/3 coking coal. The higher the metamorphic degree of the coal sample is, the higher the combustion efficiency is.