As a key enzyme, allene oxide synthase(AOS) plays an important role in the biosynthesis of jasmonic acid(JA). In order to study its function in the process and molecular mechanism of corm expansion for Gladiolus hybridus, a full-length cDNA of GhAOS, containing a 1 533 bp open reading frame(ORF) encoding 510 putative amino acids with a calculated protein molecular weight of 56.53 kD, was cloned from the corms of G. hybridus ‘Rose Supreme’ through RT-PCR and RACE technologies. The tissue-specific expression analysis using RT-PCR showed that the GhAOS was expressed in leaves, stolons, flowers, roots, corms and cormels. Moreover, its RNA level was higher in leaves and stolons. In corms, the expression level of GhAOS decreased with the increasing concentrations of salicylic acid(SA) from 0, 0.1, 0.5, 1.0 to 2.0 mmol/L.In summary, results indicate that GhAOS is a novel AOS gene and repressed by SA in mRNA level, which primarily verifies the antagonistic interaction between SA and JA in signaling pathways.