The antidepressant trimipramine(Tri) enantiomers were successfully separated by capillary electrophore-sis(CE) coupled with electrochemiluminescence(ECL) detection in aqueous-organic media. A dual cyclodextrin(CD) system combining β-CD and hydroxypropyl-β-cyclodextrin(HP-β-CD) was used as chiral selector. Acetonitrile(ACN) was added to the running buffer to improve the separation efficiency, detection sensitivity and repeatability. The me-thod was also successfully applied to the chiral separation of Tri in spiked human urine sample.