The invention discloses an adding method of a flame inhibitor of a coal mine permitted detonator explosive. The method comprises the following steps: 1, adding polyvinyl alcohol into water, and heating for dissolving to form an aqueous solution of polyvinyl alcohol; 2, adding the flame inhibitor into the cooled aqueous solution of polyvinyl alcohol, and fully stirring to form a suspension; and 3, putting the prepared explosive particles in the drum of a drum coating machine, allowing the drum to rotate, adding the suspension obtained in step 2 in a dropwise manner to wet the particles, introducing hot air for drying, adding the suspension, and repeating the above suspension addition and drying process until no suspension is residual, and drying to prepare a flame inhibitor-containing explosive. Compared with the prior art, the method has the following substantial characteristics: the coating rate of the flame inhibitor is high, so the cost is reduced; the content of the flame inhibitor coated in the explosive can be easily adjusted; the surface of the particles is uniformly coated with a water-soluble film, so the surface of the particles is smooth, and the fluidity of the particles is improved; crystals of the flame inhibitor coated on the surface of the particles unlikely generate a static effect, so the static accumulation of the particles is reduced; and polyvinyl alcohol is a water-soluble polymer, and water is used as a solvent, so no organic solvent volatilizes in the production process, and the method is nontoxic and has no pollution.