A fire-extinguishing aerosol composition for heavy current electric apparatuses is disclosed, which includes oxidant, combustible, adhesive and additive. The composition of the present invention is characterized in that the oxidant is the mixture of the potassium salt and the strontium salt, in which the content of the potassium salt oxidant is more than 20 mass % to less than or equal to 35 mass % of the total mass of the composition, and the content of the strontium salt oxidant is more than or equal to 30 mass % to less than 48 mass % of the total mass of the composition. In the fire-extinguishing aerosol composition of the present invention, the mean particle diameter of all components is less than or equal to 50 μm. After quenching the fire in a space with the heavy current electric apparatus, the fire-extinguishing aerosol composition of the present invention can ensure that the insulation resistance of the heavy current electric apparatus is more than or equal to 20 MΩ. The fire-extinguishing aerosol composition of the present invention is more reasonable than the prior art, friendly to the environment, and applicable to the heavy current electric apparatuses.