NOVELTY - A lactic acid is produced using glycerol as substrate by inoculating a culture comprising glycerol use gene and lactic acid synthetic gene into seed culture medium with glycerol, and cultivating; adding seed liquid into original fermentation medium; performing anaerobic fermentation or microaerobic fermentation; fed-batching aqueous alkali or adding solid calcium carbonate in batches to control pH value; and measuring concentration of thallus and content of glycerol and lactic acid in the fermenting process.    USE - Method for manufacture of lactic acid (claimed) and biodiesel oil.    ADVANTAGE - The method uses low-cost raw material and is capable of obtaining biological diesel oil and lactic acid of high added value, which can improve utilization rate of raw material and reduce production cost.    DETAILED DESCRIPTION - Manufacture of lactic acid by using glycerol as substrate involves:    (A) inoculating a culture comprising glycerol use gene and lactic acid synthetic gene into seed culture medium with glycerol, and cultivating at 30-37 degrees C for 20-30 hours;    (B) adding the seed liquid into original fermentation medium with 30-80 g/l glycerol;    (C) performing anaerobic fermentation or microaerobic fermentation at 37-55 degrees C, introducing air, stirring at 0-350 rpm, and adding glycerol to control glycerol concentration in the fermentation broth at 10-50 g/l;    (D) fed-batching 3-4 M aqueous alkali or adding solid calcium carbonate in batches to control pH at 5-8;    (E) measuring concentration of thallus and content of glycerol and lactic acid in the fermenting process; and    (F) when production rate of lactic acid is less than 0.3-0.5g/hr, stopping fed-batching glycerol and continuing to ferment until the concentration of remaining glycerol in the fermentation broth is reduced to be less than 5g/l, and stopping fermentation.    The glycerol comprises un-refined glycerol manufactured using chemical method, biological zymotechnics, and by-product glycerol of biological diesel oil.