The present invention relates to a signal peptide and application thereof in recombinant bacteria for producing L-glutamic acid from konjaku flour, and belongs to the field of genetic engineering and enzyme engineering. The screened and codon-optimized signal peptide, namely SEQ ID No.1 is fused, by molecular cloning and genetic engineering techniques, with B. subtilis CCTCC M 209200-sourced beta-mannanase for construction of an expression vector for expressing in L-glutamic acid high-yield production bacterial stain. For the first time, the signal peptide is reported, wherein the signal peptide can be used for mediation of recombinant bacteria Brevibacterium tianjinese SW07-1 / pMSPman, which is capable of secreting the beta-mannanase, for producing the L-glutamic acid by fermentation of the chip konjaku flour, and the yield of a 5L fermentor is 65g / L under the condition of addition of an optimal carbon source.