China's saline and alkaline land is widely distributed and large in area, which is an important reserve arable land resource and a "potential granary" for increasing food production. Soil salinization and alkalization often occur in conjunction with each other, and saline-alkaline stresses are more damaging to soybean than salt and alkaline stresses alone. Mining the genes that negatively regulate soybean"s tolerance to saline-alkaline, and creating new varieties of soybean tolerant to saline-alkaline through gene knockout is one of the effective ways to rationally develop and utilize saline and alkaline land, and to increase the yield of soybean in China. The group pre-screened one gene, Glyma.02g271000 (GmDUF247-1), which was down-regulated and expressed under salinity stress by sequencing and analyzing the transcriptome of soybean under saline-alkaline treatment. Our group screened one candidate gene Glyma.02g271000 (GmDUF247-1) in response to salinity stress by sequencing and analyzing the transcriptome of soybean under saline-alkaline treatment. The GmDUF247-1 protein contains one DUF247 structural domain and one transmembrane structural domain, and the GmDUF247-1-GFP fusion protein was found to be localized to the cell membrane using transient expression in tobacco leaves. The results of fluorescence quantitative PCR showed that the GmDUF247-1 gene had the highest expression in soybean roots, and its expression was significantly down-regulated under saline-alkaline treatment. To investigate the salinity tolerance function of GmDUF247-1, the tolerance of plants overexpressing GmDUF247-1 soybean hairy root complex under saline-alkaline was analyzed, and the results showed that, compared with the empty vector control, plants overexpressing GmDUF247-1 soybean hairy root showed more severe leaf wilting, a significant reduction in survival time, and a significant suppression of the relative growth of root length and plant height after saline-alkaline stress treatment. The relative growth of root length and plant height was significantly inhibited. It was hypothesized that GmDUF247-1 might act as a negative regulator in the response to salinity stress in soybean. In this study, we further analyzed the haplotypes of GmDUF247-1 gene in the natural population of soybean, and found that the promoter region of this gene has eight SNPs and four InDels, which can lead to alterations in the binding of transcription factors and elements, including DNA elements related to the response to adversity and growth and development. Three haplotypes of the CDS region of the GmDUF247-1 gene existed in this study. GmDUF247-1_H1 genotype was subjected to significant artificial selection. This study lays an important research foundation for subsequent systematic studies on the salinity tolerance function and breeding utilization of the GmDUF247-1 gene.