Abstract: Tetracycline antibiotics are widely used because of their high efficiency, low toxicity and broad-spectrum bacteriostasis, but with the abuse of antibiotics leading to the emergence of a large number of resistant bacteria, the medicinal value of tetracycline antibiotics gradually decreases. Although the ultra-small particle size of Ag can inactivate bacteria and even drug-resistant bacteria, it is highly toxic and easy to agglomerate when used alone. Therefore, in this study, the core-shell mesoporous Fe₃O₄@SiO₂@mTiO₂@Ag-tetracycline (FSmTA-T) composite was designed to solve the problems of antibiotic resistance, Ag nanoparticles agglomeration and strong toxicity by using the principle that the d orbital of Ag is a full electron structure and can be coordinated with the electron donor group. The results show that the particle size of the Ag quantum dots in the prepared composite is 2.84 nm, which could be bonded with the carbonyl group in tetracycline ring 3, and compared with tetracycline, the composite material has high bacteriostatic activity against Escherichia coli, Staphylococcus aureus, tetracycline-resistant Salmonella and Candida albicans, and could effectively destroy the bacterial cell wall and make it die, while the toxicity is reduced to 1/3 of the original. Therefore, its superior bacteriostatic activity can be applied to sewage treatment.