Saline-alkaline lands， which are found with large area in China， are considered as potential exploitable land resource inagriculture. Breeding of new soybean cultivars showing salt-alkaline tolerance in these regions is a way to improve the soybean production in China. Therefore， identification of the negative regulatory genes to saline-alkaline stress is of interest， and editing of them in elite varieties is able to create new soybean cultivars with salt-alkaline tolerance. Previously， we found that the gene Glyma.02g271000 （named as GmDUF247-1） was down-regulated under mixed salt-alkaline stress condition. GmDUF247-1 was annotated with one DUF247 （Domain of Unknown Function 247） domain and one transmembrane domain， and the GmDUF247-1-GFP fusion protein was observed on the cell membrane when transiently expressing in tobacco leaves. GmDUF247-1 was detected with the highest transcripts in roots， and its expression was down-regulated under mixed saline-alkaline treatment. Through generating the hairy root composite plants， the transgenic plants overexpressing GmDUF247-1 showed more wilted leaves， lower survival rates， shorter roots and shoots if compared with these lines expressing the empty vector. Based on the haplotype analysis of GmDUF247-1 in soybean population， eight SNPs and four InDels in the promoter region were detected， implying alterations potentially in the binding of growth- and stress-related transcription. Three haplotypes were identified based on the coding sequence variations， and the haplotype GmDUF247-1^H1 was detected with artificial selection. In summary， we provided the preliminary results on negative regulation of GmDUF247-1 under mixed salt-alkaline stress treatment， which will facilitate to systematically characterize its function and elucidate its potential in breeding new soybean cultivars with superior tolerance to mixed salt-alkaline stress.