Now as a feedstock for the popular biodegradable industry, the L-lactic acid have became more and more important. L-lactic acid fermentation is studied by using Rhizopus oryzae as strain and cornstarch as carbon source. The results show that compared with PVA and cotton, vegetable sponge had the best immobilizing effect. The productivity of Llactic acid is 72 - 83 g/L when the carrier size was about 8 - 10 mm, the concentration of the cartier is 15 ml vegetable sponge per 50 ml seed medium. The immobilized cells can be steadily used in repeated fermentations for more than 4 times. Immobilized by vegetable sponge will have a well appliance in L-lactic acid industry.