Abstract: The crude extraction and characterization of bacteriocin produced by Lactobacillus acidophilus were studied in this experiment.Lactobacillus acidophilus bacteriocin was crudely extracted by ethyl acetate extraction, the bacteriostasis spectrum was determined, and its pH value stability, thermal stability and protease sensitivity were analyzed.The results showed: Lactobacillus acidophilus bacteriocin presented good bacteriostasis after eliminating the interference of hydrogen peroxide and organic acids.The bacteriostasis spectrum of Lactobacillus acidophilus bacteriocin was broad, and it had obvious inhibitory effect on Escherichia coli, Anthracea, Streptococcus lactis, Bacillus subtilis and Listeria with the bacteriostasis circle diameter above 30 mm.Bacteriocin still remained 90% bacteriostatic activity after treated at 121 ℃ for 30 min, which showed good thermal stability.The optimal bacteriostatic effect was detected at pH 2.0-9.0, and the bacteriostatic activity remained 64% at pH 9.0.The bacteriostatic activity of the bacteriocin remained 62%, 79%, 75%, 73%, and 73% after treated with protease K, alkaline protease, papain, trypsin, and neutral protease, respectively.However, the activity was unchanged after treated with pepsin.The bacteriocin produced by Lactobacillus acidophilus has promising applications in food preservation and drug therapy.