A method for producing L-lactic acid by Bacillus coagulans CGMCC No.2602 belongs to the technical field of microorganisms. In the invention, Bacillus coagulans CGMCC No.2602 is adopted, and under the condition of no oxygen supply, starchiness hydrolyzed sugar or dextrose is fermented by a semicontinuous intermittent fermentation way or an inter-sugar-compensating fermentation way to generate L-lactic acid with high optical purity. The invention has the advantages that the gemma property of the Bacillus coagulans is stable, and the L-lactic acid obtained by inoculating and fermenting the starchiness hydrolyzed sugar has high optical purity and rate of conversion of sugar and acid and short fermentation period; in addition, the semicontinuous intermittent fermentation way saves the time forpreparing seeds by a continuous reladling and subculturing method, shortens the fermentation period, enhances the fermentation strength and obtains the L-lactic acid with both relatively high rate ofconversion of sugar and acid and purity.