In recent years, hydrogel has attracted wide attention in biomedical and food environmental protection because of its unique network structure and versatility, among which bio-based green functional material has become an important development direction of hydrogel. The antibacterial casein-based nanocomposite hydrogel was prepared by "semi-soluble sol-gel acidification" with casein (CA) as the base, introduced nanoparticles ZnO (ZnO NPs). The experimental results showed that the as-prepared nanocomposite hydrogel had three-dimensional three-dimensional network structure with uniform pore distribution; when ZnO NPs was 3%, the swelling rate reached up to 79.19%, whilst the tensile strength and elongation at break increased to 1.9 MPa and 137.4%，respectively ; the obtained nanocomposite hydrogel showed excellent adhesion to human skin, glass, plastic, metal; and harbored surperior antibacterial properties for E. coli and S. aureus. This research can provide a good application prospect in biomedical dressings fields.