Abstract: A micromolecule propionibacterium bacteriocin was purified from the supernate of Propionibacterium shermanii,in which the bacteriostatic activity was measured step by step.The study of preliminary purification indicated that the best desalting condition was 5 m L sample application,0.5 m L / min,manual collection,stopped collection when electrical conductivity increased to 1.5 ms / cm. The optimal gel filtration condition of superdex peptide column was 500 μL sample application,0.5 m L / min flow rate,fixed volume collection,each well volume was200 μL. The antimicrobial activity of propionbacterium bacteriocin improved 6.8 times,but the recovery rate of inbition activity was only 10.9%.The relatively molecular weight of bacteriocin was measured to be 698.9556 u by the MALDI- TOF method.It was indicated that the bacteriocin still remained activity after purification,which was sensitive to pepsin.