Abstract: Objective: Investigating the polymorphisms of variable number tandem repeat (VNTR) in Mycobacterium tuberculosis, developing high discriminatory power of VNTR typing, especially for recognizing Beijing family. Method: 22 known VNTR loci (12 MIRU, 3ETR，6 QUB and Mtub21) were assessed among 102 Mycobacterium tuberculosis strains isolated from Tianjin. Results: The 14 VNTR loci set (MIRU-10, 20, 26，27, 31，40, QUB11b，11a，18，26 and Mtub21) optimize in this study have high discriminatory power with H=0.9963. 7 loci (QUB11b，11a，18，26，MIRU-26，31，Mtub21) were highly (H>0.3), 7 loci (QUB1895，ETR-A，MIRU-10，20，27，39，4) were moderate (0.1

Key words: Mycobacterium tuberculosis, Beijing Genotype, variable number tandem repeat, Genotyping, Molecular Epidemiology