Application of glutamate dehydrogenase GdhA of Peptostreptococcus asaccharolyticus in increasing the yield of poly-γ-glutamic acid from Bacillus licheniformis. The glutamate dehydrogenase GdhA of the Bacillus licheniformis WX-02 per se is replaced with the glutamate dehydrogenase derived from the Peptostreptococcus asaccharolyticus by means of homologous recombination, which significantly increases the level of synthesizing the poly-γ-glutamic acid for the Bacillus licheniformis, and the yield of the obtained poly-γ-glutamic acid from strains is increased at least by more than 20% compared with control strains.