Abstract: To further understand features of coal oxidation in low temperature, device of blast oven and GC-950 gas chromatograph were applied to make a study of CO concentration at 80 ℃ in confined space, study shows that CO growth rate keeps constant with invariable coal temperature and production of CO increases linearly when oxygen is sufficient. Once oxygen decreases, CO growth rate is in decline with extending of soak time, and there is a certain relation between them. Meanwhile, the variation of free radicals concentrations were studied using an electron spin resonance (ESR) spectrograph at different time in the isaothermal process, which reveals coal oxidation process in microcosm. comparative study is conducted to understand particularity of critical temperature 80 ℃.