Abstract: In order to study the change rule of free radicals in the process of continuous oxygen consumption of coal, four kinds of bituminous coals with different degrees of deterioration were selected and electron paramagnetic resonance apparatus was used to study the change rule of free radicals in the process of continuous oxygen consumption of different bituminous coals from oxygen-rich to oxygen-poor under the condition of variable temperatures. The experimental results show that the species and concentration of free radicals decrease and the symmetry of free radicals increases with the increase of coal metamorphism at room temperature; with the decrease of coal particle size, the concentration of free radical in coal increases, the type remains the same, and the symmetry fluctuates; particle size distribution has great influence on free radicals, concentration, type and symmetry of coal; when the temperature keeps increasing and the oxygen supply keeps decreasing, the concentration of free radicals in coal increases and decreases, while the type and symmetry of free radicals decrease. The continuous oxygen consumption of different types of coal varies with temperature.