Bacillus laterosporus stranin 2Q9 secreted a high level of antimicrobial peptides when cells were grown in liquid NB media at 28 ℃ for 24 h. Purification was carried out by protein precipitation with 75% ethanol, anion- exchange chromatography and cation-exchange chromatography sequentially. The relative molecular weight and isoletric point of antimicrobial peptide BL2Q9 were 7 800 and 10.2 respectively. The sequencing results of MS/MS showed that the antimicrobial peptide was a new antimicrobial peptide (AMP) with low amino acid sequence similarity among the known AMPs in database.