Abstract: In this study, 18 strains of exopolysaccharides (EPS) producing lactic acid bacteria (LAB) were isolated from raw materials from different sources. By comparing the emulsifying activity of the fermentation broth and buckwheat sourdough fermented by LAB, a LAB with EPS and high emulsifying activity was obtained and used as starter in buckwheat sourdough fermentation. The effects of starter used on the baking characteristics of buckwheat sourdough bread were investigated using methods of means of rotational rheometer, laser confocal and texture analysis. The results revealed that EPS producing LAB YC'-22 strain with high emulsifying properties was identified as Lactobacillus fermentumstrain HBUAS54017 with a homology of 100%. The EPS yield of this strain was 1.63 g/L. The gluten network structure ofbread dough was strengthened after adding buckwheat sourdough fermented by LAB.Compared to control bread (CB), the specific volume of buckwheat bread added 1.0% arabic gum (AGB) and buckwheat sourdough bread (SDB) increased by 12.42% and 14.08%, respectively, while the hardness decreased by 13.90% and 22.87%, respectively.SDB bread had the highest overall acceptability and the most obvious improvement effect. Therefore, the buckwheat sourdough fermented by LAB strains with emulsifying EPS can be used as a natural bread functional ingredient.