Spindle-like Ag/ZnO nanostructure has been successfully synthesized via an ultrasonic-microwave combined assisted method. The as-prepared Ag/ZnO nanocomposites exhibited enhanced photodegradation efficiency for organic pollutants than pure ZnO and commercial TiO2 (P25) under visible light irradiation, which was probably due to the surface plasmon resonance (SPR) effect of Ag nanoparticles. The production of hydroxyl radicals ((OH)-O-center dot) under visible light irradiation was greatly promoted via loading Ag nanoparticles on the surface of ZnO nanostructures, also resulting in the improved photocatalytic activity. Moreover, the spindle-like Ag/ZnO nanocomposites displayed excellent antibacterial activities for both Gram-positive and Gram-negative bacteria. The Ag/ZnO nanocomposites could penetrate and damage cell membrane, causing the leakage of cytosol and the inactivation of respiratory chain dehydrogenase. The synergistic effect of Ag and ZnO is also beneficial for the mass production of H2O2, leading to the enhanced antibacterial activities of nanocomposites.