Abstract: According to the theories of quantum chemistry and organic chemistry, Gaussian09 software was used to simulate the chemical reaction process of coal-CH₂- functional oxidative auto-ignition water generation and carbon monoxide. The B3LYP/6-311G method was used to optimize and calculate the chemical reaction in each step of the process. Search for each possible transition state and perform a intrinsic reaction path (IRC) calculation to confirm the authenticity of each transition state obtained. Finally, according to the molecular orbital theory, the charge density calculation was carried out. It was found that the sulfur element increased the oxidation activity of -CH₂- by adding sulfur.