In this study, a homology-driven integration vector and electroporation system was developed to delete a protease gene in the pathogenic bacterium Brevibacillus laterosporus strain G4. Furthermore, an in vitro protease-deficient mutation was generated by introducing the integration vector with a 445-bp protease BLG4 fragment into B. laterosporus chromosomal target via homologous recombination. The BLG4-deficient mutant showed a significant drop in protease activity as compared to the wild-type G4 strain, but had a slight effect on bacterial growth and sporulation. The results revealed that the developed method can become an important tool for studying the molecular pathogenesis mechanisms of B. laterosporus.