Thirty seven lactic acid bacterial strains were isolated from Tibet traditional fermented milk products,and were identified to species level through physiological and biochemical characterization,as well as 16S rRNA sequence analysis method.The result showed that out of 39 isolates,37 were assigned to lactobacillus genus,including Lactobacillus casei(16),Lactobacillus paracasei(7),Lactobacillus plantarum(4),Lactobacillus fermentum(2),L.delbrueckii subsp.bulgaricus(2),Lactobacillus helveticus(1),and Lactobacillus diolivorans(3).Two strains were assigned to Leuconostoc genus.Cell free supernatant of seven L.casei and L.paracasei strains showed significant antimicrobial activity against 3 indicator pathogenic bacteria.All isolated strains had no antimicrobial activity against fungi.The possibility of organic acid or H2O2 action as antimicrobial components was eliminated by experiments.The antimicrobial components were inferred to be bacteriocin because the antimicrobial activity disappeared after cell free supernatant was treated with proteinase.