Abstract: Bi/WO₃ composite materials with visible-light-response were prepared. Semi-metal Bi⁰ with SPR effect was deposited on WO₃ surface via UV reduction method using bismuth pentahydrate Bi(NO₃)₃·5H₂O as bismuth source. Using E. coli and S. aureus as experimental objects, the photocatalytic antibacterial properties of the prepared composite materials were investigated, and the Bi loading amount was optimized via considering both the structure and photoelectrochemical properties. It is found that 0.6 mmol Bi/WO₃ can kill more than 99% of bacteria within 120 min. The antibacterial mechanism was further investigated. By adding different kinds of capture agents and combining with electron spin resonance (ESR) technology, it is found that hydroxyl radical (·OH) and superoxide radical (·O₂⁻) are the main active species causing E. coli deactivation.