Aux IAA gene family plays an essential regulatory role in the auxin signal transduction pathway and plant development In this study 51 Aux IAA genes were identified from the genome of Zanthoxylum bungeanum Zb Phylogenetic tree analysis conserved motif composition and gene structure analyses revealed that the ZbIAA genes were classified into seven subfamilies Members within the same subfamily shared a similar gene structure Furthermore 34 genes 67% exhibiting tandem repeats and segmental duplications The promoter sequences of ZbIAA genes contained numerous cis-acting elements related to plant hormones and growth development Expression profiles of ZbIAA genes during different developmental stages of Sichuan pepper thorns revealed that ZbIAA1 ZbIAA5 ZbIAA25 ZbIAA30 and ZbIAA44 had significantly higher expression levels than other members They may play an important role in the development of Sichuan pepper thorns Codon usage bias analysis showed a preference for A T-ending codons within the ZbIAA gene family with 25 preferred codons and two unbiased ones This research lays a theoretical foundation for further functional analysis of the ZbIAA gene family