Abstract: Soybean straw is an abundant,potential fermentation substrate.The most efficient means to produce fermentable sugars from soybean straw is enzymatic hydrolysis.For the sake of increasing the enzymatic hydrolysis of soybean straw and extracting the raw material for producing biodegradable plastic-lactic acid from soybean straw,enzymatic hydrolysis of soybean straw by cellulase was investigated.With initial soybean straw concentration of 5%,reducing sugar concentration and saccharification rate after enzymatic hydrolysis were 242.25 mg•g^-1 and 51.22% respectively.L-lactic acid production by Lactobacillus casei and Lactobacillus sake on cellulose and hemicellulose hydrolysate of ammonia pretreated soybean straw was also studied.7.52 g•L^-1 ,8.79 g•L^-1 and 11.07 g•L^-1 of lactic acid could be further obtained by fermentation with Lactobacillus casei and Lactobacillus sake and mix lactobacilluses.The lactic acid yields were 48.27%, 56.42% and 71.05% respectively based on glucose in hydrolysate.