Plant architecture is governed by the action of meristems. During vegetative development, the shoot apical meristem is responsible for initiating all of the above-ground structures including the nodes, internodes, leaves, axillary meristems and the inflorescence. Five barley mutants with low-tiller have been found, currently including, low number of tillers1 (lnt1.a), absent lower laterals1 (als1), intermedium-b (int-b), uniculm2 (cul2.b), uniculm4 (cul4) and semi brachytic (uzu). Specifically, the cul2.b mutant failed to develop tillers, while the lnt1.a mutant can produce 1-4 tillers. Genetic analysis indicated that two mutant phenotypes were caused by two recessive genes cul2.b and lnt1.a, respectively. In this study, two F2 populations, 279 individuals derived from BowmanxGSHO 531 and 184 individuals derived from BowmanxGSHO 1984 were developed for mapping the cul2.b and lnt1.a genes using Simple Sequence Repeats (SSR) markers. F3 populations were created to identify genotypes of F2 individuals. Ultimately, cul2.b was located between SSR markers GBM1212 and Bmag 0613 on the long arm of chromosome 6H, with distances of 12.7 and 13.2 cm to the two markers, respectively. Another five SSR markers (GBM 1319, GBM 1423, Bmag 0807, Bmag 0378 and Bmag 0003) on chromosome 6H were also found around the cul2 gene, with distances of 19.6, 33.3, 34.1, 71.5 and 80 cm to the cul2.b gene. The lnt1.a gene was positioned 7.8 cm away from GBM 1043 on chromosome 3H. This study narrowed the block of tiller development gene in the cul2 and lnt1 mutant. It is a benefit for further map-based clone of the genes.