The T9W is a variant of pig myeloid antimicrobial peptide-36 (PMAP 36) that displays efficient and specific activity against Pseudomonas aeruginosa. It may represent a promising agent for anti-pseudomonas therapies, so a large quantity of T9W is needed for pharmacological study and clinical use. Recombinant T9W was successfully produced by Bacillus subtilis WB800 N using the maltose-inducible promoter Pglv. After 36 h of induction by 5% maltose, 6 x His-SUMO-T9W was directly secreted into culture medium. Then, 6 x His-SUMO-T9W was purified by Ni-NTA affinity chromatography, and then 32 mg/L of fusion peptide was obtained. Then, the purified 6 x His-SUMO-T9W was digested by SUMO protease, thus releasing the recombinant T9W. Recombinant T9W showed high antimicrobial activity against Pseudomonas aeruginosa and extremely weak activity against other gram-negative (Escherichia coli, Salmonella typhimurium) and gram-positive bacteria (Staphylococcus epidermidis, Staphylococcus aureus). When the concentration of recombinant T9W reached the maximum (256 04), no hemolytic activity was observed. Recombinant T9W has similar activity to synthetic T9W. These results suggested that this method provided an economical and environmentally friendly approach to producing anti-pseudomonas agent T9W in Bacillus subtilis.