Abstract: The bHLH TFs (basic Helix-Loop-Helix transcription factors) family is widely found in microorganisms, plants and animals, and is the second largest family of transcription factors. In this study, Citrus sinensis was used as the experimental material, the physicochemical properties, phylogeny, chromosome distribution, conserved motif and protein interaction bioinformatics of bHLH gene were analyzed by genome-wide database search, and their expression in different tissues was discussed. Studies have shown that 126 bHLH genes were identified. Among them, 112 bHLH genes are distributed on 9 chromosomes, 14 bHLH genes are located in uncertain locations. Phylogenetic analysis indicated that the C. sinensis bHLH gene family can be divided into 16 subfamilies, and most genes in a given subfamily have similar gene structures and conserved motifs. Multiple bHLH gene interactions in C. sinensis regulate the development of flower organogenesis, light morphogenesis and anthocyanin synthesis. The tissue expression pattern of CsbHLH gene indicates that most members are in callus, leaves, flowers and fruits are expressed. This study laid the foundation for the functional study of the CsbHLH gene and contributed to the functional study of the bHLH gene in other plant species.