Abstract: In order to explore the influence of different oxygen concentrations in goaf on the micro-characteristics of low-temperature oxidation process of coal, a self-built low-temperature oxidation simulation experimental system was used to simulate the natural oxidation state of coal at different depths of goaf. Based on electron spin resonance spectroscopy(ESR) technology, the free radicals in coal oxidation at low temperature under different oxygen concentrations were analyzed, and the release of gaseous products in coal oxidation process was determined. The results show that at the temperature node of 130 ℃, the change is from slow to fast. Coal body changes from slow oxidation to fast oxidation, but the g factor is between 2.001 41 and 2.002 034, with little change. With the increase of oxygen concentration, the variation trend of each parameter with oxidation temperature remains unchanged, but the overall variation increases gradually. When the oxygen concentration is less than 9%, the reaction of free radicals is slow at low temperature, and the generation of CO lags behind obviously. When oxygen concentration is more than 9%, the probability of coal-oxygen combination increases. The increase of temperature is more likely to stimulate the free radical reaction, and the CO concentration increases exponentially.