The SOS signal transduction pathway is a salt stress signal response pathway in plants, and serine/threonine protein kinase (SOS2) plays an important role in this pathway. Based on the cucumber genome database, this study used bioinformatics and quantitative realtime PCR and other methods to identify the whole genome of cucumber SOS2 gene family, and systematically analyzed its expression characteristics. The results showed that: (1) a total of 15 SOS2 genes (CsSOS21-CsSOS215) were identified in the cucumber genome, which were distributed unevenly on 5 chromosomes, and the subcellular localization showed that SOS2 protein were mainly located in the plasma membrane. (2) Phylogenetic analysis showed that CsSOS22 and CsSOS26 were more closely related to AtSOS2. (3) The prediction of cisacting elements shows that the promoter sequence of SOS2 gene mainly contains droughtinduced and defensestress response elements. (4) Structural analysis showed that the sequence of conserved motifs contained in SOS2 protein were completely consistent, and mainly contained STKc and NAF conserved domains, which may play a regulatory role in gene response to salt stress. (5) Quantitative realtime PCR test showed that the SOS2 gene family is mainly upregulated in cucumber roots and leaves in response to salt stress. Among them, 6 genes were upregulated in response to salt stress on the first day of treatment. As the treatment time prolonged, gene expression was downregulated under salt stress. Addition of polyamines significantly increased the expression of CsSOS21—CsSOS25, CsSOS28, CsSOS29, CsSOS212 and CsSOS215 in different tissues. This shows that polyamines can induce the expression of cucumber SOS2 gene family under salt stress, and then participate in the regulation of plant salt tolerance molecular network.