The volatile oil of zanthoxylum was extracted by ultrasound-assisted extraction method and its chemical composition was analyzed by GC-MS. Using an orthogonal array design, we determined the optimal extraction conditions to be 20 min, 60 kHz and 1:30 (g/mL) for extraction time, ultrasound frequency and solid-to-solvent ratio, respectively. The maximum yield of volatile oil under the optimized conditions was 8.61%. A total of 33 compounds were detected in the volatile oil, of which 28 were identified for the fi rst time, and its chemical composition was analyzed by GC-MS. accounting for 96.96% of the total volatile compounds. The major compounds identified were linoleic acid (27.43%), oleic acid (15.77%), limonene (14.25%), linalool (8.36%), linolcnic acid (6.85%), β-ocimene (3.78%), 1-(2- hydroxy-methyl-pyrrol-1-yl ) ketone (2.74%), linaly acetate (2.72%), and β-myrcene (2.52%) etc