Abstract: To explore the sequence characteristics and genome composition of the TT8 gene in Brassica crops, Arabidopsis thaliana TT8 gene was used as the seed sequence. BLAST alignment was adopted to systematically identify the Brassica(B. rapa, B. oleracea, B. napus, B. juncea, B. nigra) homologous gene, and the nucleotide and amino acid sequences were compared and analyzed. The results showed that 7 AtTT8 homologous genes were identified in Brassica, including 2 in B. napus, 1 in B. rapa, 1 in B. oleracea, 2 in B. juncea, 1 in B. nigra. There were no significant differences in basic physical and chemical properties, subcellular localization and protein tertiary structure of 7 TT8 genes in Brassica. The amino acid sequences are highly similar and belong to bHLH superfamily. The 2 TT8 homologous genes of B. napus are closely related to B. rapa and B. oleracea. Four sgRNA sites were highly conserved in the 7 AtTT8 homologous genes which were speculated to be highly correlated with the function of the TT8 gene. In this study, re-sequencing data derived from 43 B. napus germplasm accessions was used to analyze. A total of 11 polymorphic loci were detected in 2 homologous genes of TT8. This includes 4 SNP and 7 InDel, with a total frequency of 0.00109 and 0.00199, respectively. Both are located in the 5'UTR region.