Abstract: Lactobacillin XH2 bacteriocin produced by Lactobacillus acidophilus was extracted by two methods, chloroform extraction and ammonium sulfate salting-out.The bacteriostatic diameter of the chloroform extract was17.40 mm, and that of the precipitate, obtained from ammonium sulfate salting- out, was 15.50 mm.By comparison, the antibacterial effect with 60% ~80% saturation gradient was significant.After purified by cellufine A-500 anionexchange, the bacteriostasis potency and specific activity of the two crude extracts were significantly increased to380.60 Au /mL and 355.60 Au /mL, 5.55 Au /μg and 9.96 Au /μg, which purification factors were 15.86 and 28.46 respectively.Tricine-SDS-PAGE showed that its molecular weight was between 14.4~20.1ku.