The invention provides antibacterial hydrogel and a preparation method thereof. The antibacterial hydrogel comprises a base layer, a gel layer and a protection layer. The gel layer is prepared by thefollowing components in part by weight: 10-38 parts of gelatin, 16-25 parts of bacterial cellulose, 12-18 parts of polyvinyl alcohol, 3-12 parts of silver ions, 1-4 parts of nanometer titanium dioxideand 1-2 parts of surfactant; the gel layer has a mesh with a thickness of 0.5-3 mm, and nanometer aluminum oxide has a particle size of 5-25 nm. The hydrogel provided in the invention is simple in preparation method, comfortable to use, incapable of causing allergy, excellent in antibacterial effect and good in air permeability.