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In this study, an oscillating-fan cooling device using electromagnetic force has been proposed. The device consists of two oscillating-fans flapping back and forth. It requires only one electromagnet and two elastic blades with one magnet on each of them. The electromagnet and two elastic blades are situated on a base and arranged accordingly. And thus, the electromagnetic force generated by the electromagnet can actuate the blades. The main advantage of this cooling device compared to a rotary fan is its simple structure because there is no bearing and motor in the cooling device. Moreover, the simplicity of the device makes it a highly reliable and low cost cooling device. The driving current can be either DC PWM or AC under 8 V -12 V so it is compatible to most electronic devices. The dimensions of the model under operation is 55 mm (L) * 50 mm (W) * 15 mm (H). The thermal resistance of a small heat sink can be decreased from 4.37 to 1.16 by using the combination of two blowers while consuming 2.4 W. Model -A can decreases the thermal resistance from 4.37 to 1.27 and consumes 25% power of that of the two blowers consume. . Nomenclature IntroductionReliability is an extremely important issue for outdoor electronic devices. Currently, most of outdoor cooling solutions takes advantage of natural convection because available axial and radial fans shows degradation in outdoor environment. The reason is that the ball bearings have a low mean time to failure (MTTF) [1] due to dust, temperature, humidity, salt spray. These factors increase the friction between a shaft and a ball bearing. In previous studies, researchers proposed non-bearing cooling solution such as piezoelectric (PZT) fans. It is a rectangular elastic sheet bonded with a PZT plate which is able to vibrate periodically by applying 50 V -100 V alternating current. This vibration induces airflow to improve convective heat transfer while consuming 0.08 W ~ 0.15 W. The fundamental, the cooling ability, and the vibration phenomenon have been investigated clearly [2,3,4]. Recently, many studies on PZT fan array have been published. The purpose of these studies is to enhance the cooling ability of a PZT fan cooling system by increasing the fan number of the system or combining the system with a heat sink [5,6,7,8]. However, the adhesive layer between the elastic sheet and the PZT plate shows degradation. Additionally, its price is high when comparing to a rotary fan and an inverter drive circuit is necessary to transform low voltage DC to high voltage AC for driving it. In this study, an oscillating-fan cooling device using electromagnetic force has been proposed. The main advantages are simple structure, high reliability and low cost. Moreover, the driving current can be either DC PWM or AC under 5 V -12 V so it is compatible to most electronic devices.