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<i>Panax ginseng C. A. Meyer</i> (<i>Ginseng</i>) is one of the most used traditional Chinese herbal medicines, with its roots being used as the main common medicinal parts; its therapeutic potential has garnered significant attention. <i>AUXIN/INDOLE-3-ACETIC ACID</i> (<i>Aux/IAA</i>) is a family of early auxin-responsive genes capable of regulating root development in plants through the auxin signaling pathway. In the present study, 84 <i>Aux/IAA</i> genes were identified from the ginseng genome and their complexity and diversity were determined through their protein domains, phylogenetic relationships, gene structures, and cis-acting element predictions. Phylogenetic analyses classified PgIAA into six subgroups, with members in the same group showing greater sequence similarity. Analyses of interspecific collinearity suggest that segmental duplications likely drove the evolution of <i>PgIAA</i> genes, followed by purifying selection. An analysis of cis-regulatory elements suggested that <i>PgIAA</i> family genes may be involved in the regulation of plant hormones. RNA-seq data show that the expression pattern of <i>Aux/IAA</i> genes in <i>Ginseng</i> is tissue-specific, and <i>PgIAA02</i> and <i>PgIAA36</i> are specifically highly expressed in lateral, fibrous, and arm roots, suggesting their potential function in root development. The <i>PgIAA02</i> overexpression lines exhibited an inhibition of lateral root growth in <i>Ginseng</i>. In addition, yeast two-hybrid and subcellular localization experiments showed that PgIAA02 interacted with PgARF22/PgARF36 (ARF: auxin response factor) in the nucleus and participated in the biological process of root development. The above results lay the foundation for an in-depth study of Aux/IAA and provide preliminary information for further research on the role of the <i>Aux/IAA</i> gene family in the root development of <i>Ginseng</i>.