In order to further analyze the functions of BXL family genes in the development of stem,16 genes encoding putative BXL proteins were identified in the whole genome of Brassica juncea var. tumida with bioinformatics methods. The gene structure and conserved motifs,chromosomal distribution and gene expression during the swelling of stem of BjuBXL family genes and the physicochemical properties of BjuBXL family protein were systematically analyzed. The results showed that 16 BjuBXL genes were classified into 7 categories and 2 sub-families according to the phylogenetic tree analysis,among which BjuBXL1-1，BjuBXL1-2，BjuBXL1-3 and BjuBXL1-4 are closely related to AtBXL1,which is involved in cell wall metabolism and plant development in Arabidopsis. 7 BjuBXL genes were located in 5 chromosomes of A subgenomes and 8 BjuBXL genes are located in 4 chromosomes of B subgenomes. The results of fluorescence quantitative PCR analyses showed that the transcriptional levels of BjuBXL1-1and BjuBXL1-2 were up-regulated obviously during the swelling of stem. The expression in the inner pith (P2-P4) were significantly higher than that in regions of the outer pith of swollen stem (P1),indicating that BjuBXL1-1 and BjuBXL1-2 may play an essential role in the cell wall metabolism of inner pith during the swelling of stem.