Abstract: Bioinformatic analysis was used to identify and analyze BLH gene family members of mustard leaf at the whole genome level， and aimed to answer the biological question of whether members of mustard BLH gene family participated in regulating leaf shape variation. After gene expression analysis， candidate genes involved in leaf shape variation were identified. The results showed that the identified 45 BLH genes can be divided into 13 subfamilies. The members of BLH gene family were unevenly distributed on 17 chromosomes except B07 chromosome and all of them were located in the nucleus. The analysis of cis-acting elements in the promoter region showed that the promoter sequence of BLH gene contained several cis-acting elements related to hormonal response and abiotic stress. Mustard BjBLH family genes were expressed differently in different tissues. Among them， the expression content of BjBLH4-1 and BjBLH4-2 in the first， second and third true leaves of split leaf mustard was significantly higher than that in sawtooth leaf mustard leaves. These two genes may be involved in the regulation of leaf shape of mustard.