Abstract: Spontaneous combustion of coal is one of the main problems in coal mine safe production. The oxidized coal recrudescence should be paid enough attention at the unsealing stage. To reveal the re-ignition characteristics of coal with different oxidation levels,the research was conducted on the development of coal spontaneous combustion at each stage. The test system for spontaneous index gases was developed to analyze the occurrence and development of index gases produced by coal with different oxidation levels,and Fourier transform infrared spectroscopy was used to investi-gate the characteristics of functional group by the qualitative analysis of absorbance and the quantitative analysis of peak area. The results show that the determination index for coal spontaneous combustion tendency is Iym < I80 ℃ yh < I40 ℃ yh