The fermentative nature of five lactic acid bacteria was studied by using saccharified kidney beans. The production of lactic acid of lactobacillus acidophilus (La) was the one with highest yield and quickest production rate. The optimal mixes cultures was Lactobacillus acidophilus (La) ， Lactobacillus plantarum（Lp）and Bifidobacterium bifidum (Bb). The optimum proportion of species was La:Lp:Bb= 2: 1: 1. Soybean milk can promote the growth of the lactic acid bacteria.