Abstract: Staphylococcus aureus,Bacillus subtilis, Escherichia.coli were treated by salicylic acid with different concentrations，discussed inhibitory effect and calculated the rate of inhibition with the different concentrations of the salicylic acid solution. The result showed that: The salicylic acid has the very obvious inhibitory effects to Staphylococcus aureus,Bacillus subtilis, Escherichia.coli; Moreover its inhibitory effects presents the density effect. The bacteriostasis effect is getting more and more obvious with the concentration increase of salicylic acid. The inhibitory effect is strongest to Staphylococcus aureus，and second to Bacillus subtilis, and weakest to Escherichia.coli.