Abstract: This study determined the changes of the acidity,viable count,electropherogram,extracellular,polysaccharide content,viscosity in the process of fermenting soymilk by Lactobacillus plantarum 45,Lactobacillus plantarum 571,Lactobacillus casei,Lactobacillus acidophilus,Lactobacillus rhamnosus and the combined Viniflora Prelude PL09 in order to study the growth characteristics of different lactic acid bacteria in soymilk and the characteristics of fermentation of soymilk by lactic acid bacteria and yeast. The results showed that:the pH of Lactobacillus plantarum 45 and Lactobacillus plantarum 571 reached 4.43 and 4.42 after fermented soymilk 8 h,and the viable count reached 3.11×10⁸ and 2.78×10⁸ CFU/mL,respectively. The total sugar content reduced faster. Lactobacillus rhamnosus and Lactobacillus casei produced extracellular polysaccharides of 180.82 μg/mL and 174.45 μg/mL when fermented in soymilk,respectively. When lactic acid bacteria and yeast were combined for soymilk fermentation,Viniflora prelude PL09 could promote acid production and increase viable count and viscosity of the products,which provided guidance for the development of co-fermented soymilk for lactic acid bacteria and yeast.