Laboratorial experiments of coal spontaneous combustion under non-isothermal conditions were conducted using a self-made instrument aimed at investigating the characteristics of carbon monoxide emissions and kinetic characteristics. The impacts of coal rank, particle size, and oxygen content on the CO production during the decaying process of spontaneous combustion were studied. The experimental results demonstrated that coal particle size had a significant influence on the spontaneous combustion at high temperatures and coals of a large particle size decreased slowly in terms of the total CO production. Meanwhile, it is also found that even if the oxygen content was as low as 3%, the oxidation reaction of coal still existed, liberating CO and heat at the same time. Therefore, stricter standards were recommended when judging whether or not a spontaneous combustion had been extinguished in gobs. Additionally, the studies on oxidation kinetics of coal implied that the activation energy was dependent both on the oxidation temperatures and coal properties. Oxidation temperatures affect the magnitude of activation energy, while coal properties impact the response of activation energy to the oxygen contents.