Abstract: Due to excessive CO, impacting the coal mine spontaneous combustion forecast index system..Taking Lin Nancang as an example ,From two aspects of the microstructure of coal and the external environment condition of CO to study the seepage law. Due to the low degree of metamorphism of coal, the structure of the big holes develop rich, and contains a large number of oxygen containing functional groups and free radicals, The permeability of CO in coal seams is much less than that of gas under different conditions, With the gas pressure change trend in general, and more sensitive to the temperature. When the external pressure is relatively small, the CO permeability decreases with the increase of temperature, and with the increase of confining pressure, the effect of CO permeability gradually weakened..When the confining pressure is greater than 3.0MPa, the pores in the low rank coal are severely damaged, the large pore structure disappears, and the CO permeability decreases, which is almost not affected by the change of the external conditions, Finally, the influence factors of CO permeability in coal seam are analyzed by using principal component analysis method and SPSS software, finally,getting two main influence factors, the porosity and confined pressure.