This experiment aimed to construct an integrative expression vector pHSG398–16S–lipA, and expressed gene Pseudomonas aeruginosa lipase (LipA) in Bacillus subtilis pab02. A pair of primers was designed based on sequence of gene LipA, and its P. aeruginosa A05 was cloned and sequenced, the followed by the construction of integrative expression plasmid pHSG398–16S–lipA, then it was transformed into Bacillus subtilis pab02 for expression. The experiment obtained a 1 092 bp length of LipA encoded with 311 amino acids, contained a signal peptide with 26 amino acids and a mature peptide with 285 amino acids, it shared 98% homology with gene lipase A of P. aeruginosa (Accession No. AB290342). The integrative expression plasmid pHSG398–16S–lipA was successfully constructed and transformed into B .subtilis pab02. Result from SDS–PAGE analysis showed that the lipase A was successfully expressed and its relative molecule weight was about 37 000.