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Gibberellic acid-stimulated <i>Arabidopsis</i> (GASA) proteins, as cysteine-rich peptides (CRPs), play roles in development and reproduction and biotic and abiotic stresses. Although the <i>GASA</i> gene family has been identified in plants, the knowledge about GASAs in <i>Populus euphratica</i>, the woody model plant for studying abiotic stress, remains limited. Here, we referenced the well-sequenced <i>Populus trichocarpa</i> genome, and identified the GASAs in the whole genome of <i>P. euphratica</i> and <i>P. trichocarpa</i>. 21 candidate genes in <i>P. trichocarpa</i> and 19 candidate genes in <i>P. euphratica</i> were identified and categorized into three subfamilies by phylogenetic analysis. Most GASAs with signal peptides were located extracellularly. The <i>GASA</i> genes in <i>Populus</i> have experienced multiple gene duplication events, especially in the subfamily A. The evolution of the subfamily A, with the largest number of members, can be attributed to whole-genome duplication (WGD) and tandem duplication (TD). Collinearity analysis showed that WGD genes played a leading role in the evolution of <i>GASA</i> genes subfamily B. The expression patterns of <i>P. trichocarpa</i> and <i>P. euphratica</i> were investigated using the PlantGenIE database and the real-time quantitative PCR (qRT-PCR), respectively. <i>GASA</i> genes in <i>P. trichocarpa</i> and <i>P. euphratica</i> were mainly expressed in young tissues and organs, and almost rarely expressed in mature leaves. <i>GASA</i> genes in <i>P. euphratica</i> leaves were also widely involved in hormone responses and drought stress responses. GUS activity assay showed that PeuGASA15 was widely present in various organs of the plant, especially in vascular bundles, and was induced by auxin and inhibited by mannitol dramatically. In summary, this present study provides a theoretical foundation for further research on the function of <i>GASA</i> genes in <i>P. euphratica</i>.