Abstract: The abuse of antibiotics leads to the emergence of a large number of drug-resistant bacteria, which poses a serious threat to health and social economy. Therefore, it is urgent to develop new antibacterial agents to solve the problem of bacterial drug resistance. In this paper, silver trifluoroacetate (CF₃COOAg) as raw material, using chemical reduction method to prepare nano-silver (Ag NPs) particles, and ultrasonic assisted coordination with 4-hydroxycoumarin to prepare 4-hydroxycoumarin-Ag NPs new composite antibacterial material. TEM, XRD, XPS, UV-Vis, FTIR, Zeta potential and theoretical calculation were used for characterization. Gram-negative bacteria E.coli, Gram-positive bacteria S. aureus and drug-resistant bacteria T-Salmonella were used as model bacteria to study the synergistic bacteriostatic activity and bacteriostatic mechanism of 4-hydroxycoumarin-Ag. Compared with Ag NPs, the antibacterial efficiency of the composite material for E.coli, S. aureus and T-Salmonella has been improved 62.5%, 37.5% and 44.4% respectively. When the concentration of the composite material was 150 μg/mL, the bacteriostatic rate of the tested bacteria could reach 99.9% within 60 min. The inhibition mechanism showed that the composite material could significantly destroy the bacterial cell wall and enter the bacterial interior to inhibit the bacterial respiratory system. The material not only has the unique bactericidal properties of inorganic antibacterial agent and organic antibacterial agent, but also has stronger antibacterial activity and can solve the problem of bacterial resistance, which can provide scientific basis for the modification of antibiotics and the development of new antibacterial agent.