The invention provides an accelerated copper decomposition additive as well as a preparation method and application thereof. The accelerated copper decomposition additive has a structure shown as a formula (I), in the formula (1), n is greater than or equal to 6 but smaller than or equal to 10. The fast copper decomposition additive provided by the invention has disulfide bonds and sulfonic groups; more importantly, carbon chain structures with the proper length are introduced into the molecules, the molecule water solubility of the additives is ensured; the compactness of the additive molecule adsorbed on the surface of the copper surface is increased, so that chloride ions can be better cooperated to accelerate the copper ion decomposition in the electric plating process. The acceleratedcopper decomposition additive provided by the invention has the advantages that the acceleration effect is high; the further prepared electric plating liquid meets the hole filling requirements of blind holes with a high aspect ratio; meanwhile, the electric plating production efficiency can be improved. Experiment results show that when the accelerated copper decomposition additive provided by the invention is applied to copper electric plating liquid, the super equal corner electric plating requirements of the blind hole with the aspect ratio exceeding 1 can be met; the accelerated copper decomposition additive adapts to the electronic product development directions; wide application prospects are realized.