The invention discloses a tobacco axillary bud inhibitor additive. The additive comprises 40%-60% of trisiloxane polyoxyethylene ether, 15%-20% of eucalyptus oil, 4%-8% of cationic surface active agent, 6%-12% of nonionic surface active agent and the balance of diluent. Added into the present commonly used tobacco axillary bud inhibitor, the tobacco axillary bud inhibitor additive disclosed by the invention has good physical compatibility and chemical suitability, and can be used for remarkably reducing the interfacial tension of the tobacco axillary bud inhibitor liquid medicine, enabling the liquid medicine to quickly soak plant leaf axils, expanding the liquid medicine as a liquid membrane instead of the original water droplet-like flow, promoting the effective ingredients of the axillary bud inhibitor to quickly permeate into the epidermis after the liquid medicine membrane wets the leaf axils, and effectively restricting the growth of the axillary bud.