In this paper， the antimicrobial activity of fermentation supernatant and bacteriocin produced by Lactobacillus salivarius O2A against Salmonella was studied. The effect of metal ions-bacteriocin against Salmonella and its mechanism were investigated. Alone bacteriocin and metal ions-bacteriocin had good bacteriostatic effects on Salmonella. The growth curve of different antimicrobial agents on Salmonella changed greatly after treatment for 18 h， and the bacteriostatic effects was better in the Zn2+（30 mmol/L） - fermentation supernatant and Zn2+（30 mmol/L） -bacteriocin. Compared with the standard Salmonella strain， the results of scanning electron microscope and transmission electron microscope show that the micromorphology of the treated strain was destroyed to varying degrees， among which the most serious damage was caused by the Zn2+（30 mmol/L） -bacteriocin. The mechanism of bacteriostasis may be to destroy the cell wall and cell membrane by destroying the integrity of the cell structure， thus inhibiting the growth of bacteria even killing bacteria.