Abstract: The special occurrence characteristics of steeply coal seam in Xinjiang region determine that underground mining face needs to adopt blasting to carry out pre-crack and loose before working face mining. But permissible explosive process of coal mine will produce large amounts of toxic gases, such as CO, NO and NO₂, these gases will not only harm the health of mine workers, but also seriously disturbed the early prediction accuracy degree of coal mine spontaneous combustion. To this end, in a typical steeply inclined fully mechanized caving face, using a gas concentration analysis, we study the harmful gas generating law in return current after advanced blasting and pre-splitting, and get the generated absolute amount of CO of unit mass three-level mine-used permitted emulsion explosives after the complete explosion.