The invention belongs to the technical field of daily chemical detergents and particularly relates to an antibacterial agent combination and a preparation method and application thereof in antibacterial dish washing liquid. The antibacterial agent combination consists of long-chain alkyl betaines @ graphene quantum dots and a natural plant extract, and the mass ratio of the long-chain alkyl betaines @ graphene quantum dots to the natural plant extract is (1:8)-(1:1), wherein the natural plant extract is a mixture of one or more of an ammi visnaga extract, a cistus incanus extract and a phrymaleptostachya extract. According to the method, the natural plant-derived antibacterial agent is compounded with nano-antibacterial materials, namely the graphene quantum dots (GQDs) so that not only can the efficient quick-acting effect of the GQDs antibacterial nano material be utilized, but also the advantages of environmental protection property, complexity, broad-spectrum antibacterial property, resistance to generation of drug resistance of bacteria and the like of natural plant antibacterial components can be utilized, correspondingly a synergistic antibacterial effect is achieved, and anew efficient and environmentally friendly compound antibacterial agent is developed.