Abstract: The characteristics of antibacterial substances of Lactobacillus pentosus S1- 4, isolated from the sour cabbage juice in the east aria Inner Mogolia, were tested for Escherichia coli 3301 as the indicator by the double agar diffusion method. The results showed that the antibacterial activity of strain S1- 4 was not destroyed after treatment with papain, but destroyed after treatment with pepsin and trypsin. This antibacterial substances of Lactobacillus pentosus S1-4 showed good thermal stability and stable antibacterial activity under acidic conditions in p H3.5 ~ 5.5. The inhibitory activity of this strain fermentation supernatant was not affected by some chemical agents and ultraviolet irradiation treatment.