The invention provides a coal-fired combustion improver with high stability. The coal-fired combustion improver is innovatively characterized by comprising the following components in percentage by weight: 20-30% of an oxidizing agent, 2-8% of a stabilizer, 20-30% of a catalyst, 2-3% of a dispersing agent, 10-20% of an emulsifier and 10-20% of a penetrating agent, wherein the stabilizer comprises 3,5-ditert-butyl-4-hydroxybenzoyl hydrazine, xylogen, silica powder, sodium sulfanilate and zinc stearate, or 3-methyl-5-tert-butyl-4-hydroxybenzoyl hydrazine, xylogen, silica powder, sodium sulfanilate and zinc stearate. According to the coal-fired combustion improver disclosed by the invention, the effect of adding the stabilizer into the coal is to mainly achieve the effects of delaying the decomposition rate after the oxidizing agent is heated and increasing the action time in the combustion system, and then the actual combustion effect is improved.