The application of electrohydrodynamic (EHD) technique on boiling heat transfer enhancement outside a tube was investigated experimentally. Rll and R123 were used as working fluids .The experimental rig is a smoothly copper tube of 25mm OD and 400mm long. Six copper wires, each with a diameter of 2mm and located 5mm away from the heat transfer surface served as the high-voltage electrodes. The electrodes were oriented at 60° intervals. Comparison between the EHD enhancement factors of R11 and R123 at different heat flux and different voltages was conducted. The results show that R123 has a much better response to the EHD effect than R11, the EHD enhancement factor decreased with the heat flux, and the power consumption by EHD high voltage supplier is different for Rll and R123.