A Bacillus coagulans ( BCS 13002) isolated from pickle was identified by using 16S RNA and on the basis of physiology and biochemistry,and the effects of carbon source and neutralizer on the production of L-lactic acid were analyzed.Then,the fed-batch fermentation with glucose and the synchronous saccharifying fermentation ( SSF) with corn starch were respectively carried out at 5L fermentation tanks.The results show that ( 1) glucose is a kind of ideal carbon source,while xylose and corn starch are not beneficial to the production of L-lactic acid; ( 2) as a kind of neutralizer,NaOH is better than Ca( OH) ₂ and CaCO₃ ; ( 3) through the fed-batch fermentation with glucose in a tank,the L-lactic acid content reaches up to 115. 86 g /L with a sugar acid conversion ratio of about 82. 31%,and MnSO₄·H₂O and MgCl₂·6H₂O play a special role in the fermentation; and ( 4) through the synchronous saccharifying fermentation with corn starch,the L-lactic acid content reaches up to 123. 3 g /L,with a sugar acid conversion ratio of 70. 03 % and an optical purity of L-lactic acid of more than 99. 8%.