A sensitive determination method for pethidine based on capillary electrophoresis-electrochemiluminescence detection was described. Analysis conditions affecting separation and detection were discussed and optimized in detail. The mixture solution of 5 mmol/L Ru(bpy)32+ and 50 mmol/L phosphate buffer at pH 7.46 were added to the detection reservoir. End-column detection of pethidine was performed. Sensitive electrochemiluminescence detection was obtained at applied voltage of 1.20 V. A baseline separation of pethidine was achieved using a phosphate running buffer at pH 7.46 by electrokinetic injection for 10 s at 10 kV. A detection limit of 5.0×10-8 M (S/N=3) was achieved.