The invention relates to a method for efficiently expressing Bombyx mori recombinant antibacterial peptides by using lactose culture medium, comprising the steps of (1), using intestinal tissues of five-instar seven-days-old silkworms as a material to extract total RNA, designing three pairs of specific primers, carrying out RT-PCR (reverse transcription-polymerase chain reaction) to amplify Bombyx mori antibacterial peptide cecropinB6, cecropinD and moricin genes, detecting PCR products by 2.5% agarose gel electrophoresis, and purifying BmcecropinB6, BmcecropinD and Bmmoricin by using a gel extraction kit; (2), subjecting three antibacterial peptide genes and pET-32a expression vector respectively double-enzyme digestion by using NcoI / XhoI to establish pET32a-BmcecropinB6, pET32a-BmcecropinD, pET32a-Bmmorincin expression vectors, and sequencing by dideoxy chain termination; (3), using a lactose medium method to induce the expression of BmcecropinB6, BmcecropinD and Bmmoricin antibacterial peptides. The expression yield of BmcecropinB6, BmcecropinD and Bmmoricin recombinant proteins is significantly increased, and new technical choices are provided for the application in the fields such as purification and activity identification for Bombyx mori peptides, and cosmetics.