In this study, we investigated subcooled flow boiling performance enhanced by combining effect of electric field and micro-structured surface. Thirteen micro-slits, 1mm width and 28mm length, were cut into a thin flat electrode for generating the electric filed that was placed above the boiling surface in the flow boiling channel (called as micro-slit-channel). A dielectric liquid of HFE-7000 was selected for the subcooled flow boiling. The boiling surface was electrically deposited with fine diamond particles (diameters of 20 and 1.5µm). Experimental results were compared with the flow boiling model enhanced by the electric field which was derived by one of the authors. To avoid the occurrence of cavitation in the liquid at a saturation temperature due to the decrease in pressure by rotating a pump blade, the liquid was applied at gauge pressures of 20, 70, and 128 kPa. The flow boiling experiments were conducted at mass flow rates of 1.67, 3.33, and 5.00 g/s, subcooling degrees of 5, 10, and 15 K, and electric fields of 0 to −5 kV/mm. The experimental results showed that critical heat flux (CHF) can be strongly improved from 16 to 80 W/cm² by the application of electric field. A series of boiling phases from subcooled boiling to reaching the CHF were observed by a high-speed camera. The predicted results based on the flow boiling model showed a good agreement with the experimental results within ± 20%.