NHX2 belongs to the CPA1 gene family and encodes a Na⁺/H⁺ reverse transporter which controls the uptake of active K⁺ in vacuolar membrane and regulates the closure of stomatal. In this study, the NHX2 gene was cloned by PCR from the salttolerant plant Spartina alterniflora and transferred into Arabidopsis thaliana for function identification. The results showed that: (1) the fulllength sequence of NHX2 (1 602 bp), encodes 533 amino acids, which was named SaNHX2 gene. The molecular weight of SaNHX2 protein was about 58.65 kD and located in the nucleus and cell membrane. These results indicate that SaNHX2 gene may play a role in transcriptional regulation. (2) The qRTPCR analysis results indicated that the expression of SaNHX2 gene was upregulated in leaves and roots of S. alterniflora under ABA, NaCl and drought stresses. (3) In order to identify its function, plant expression vector was constructed and SaNHX2 gene was transformed into A. thaliana. After high salt stress treatment, the length of root, the total chlorophyll content and the expression of related stress response genes of transgenic A. thaliana with SaNHX2 gene were all higher than those of transgenic A. thaliana without SaNHX2 gene. The results indicated that SaNHX2 gene may play a regulatory role in salt stress regulation and may be an important candidate gene for improving crop salt tolerance.