In order to study the antibacterial effect of Sodium Benzoate and Potassium Sorbate on E.coli and Staphylococcus aureus.Certain density bacterial suspension was added into the liquid culture medium included of different concentration of Sodium Benzoate and Potassium Sorbate to cultivate for 18 hours,and then the values of OD determined.The results showed that Sodium Benzoate（≥0.2g/L） and Potassium Sorbate（≥0.3g/L） had significant antibacterial effect on the two bacteria.The antibacterial effect gradually increased along with the increasing of concentration of Sodium Benzoate and Potassium Sorbate;The antibacterial effect of Sodium Benzoate was better than Potassium Sorbate at the same concentration.