Light emitting diodes (LEDs) have advantages such as high efficiency, long life, and good control compared to conventional incandescent lamps. LEDs are also made from environmentally friendly materials. Therefore, LEDs are expected to be the next generation of light sources. The temperature rise of an LED chip deteriorates the efficiency and lifetime of the LED. Thermal grease is filled in the air gap between the contact points to reduce the thermal contact resistance. Since the thermal dissipation is significant in LEDs, the temperature of the LED chip should be cooled down efficiently. In this paper, carbon nano grease is manufactured by adding carbon nano tubes (CNTs) into the thermal grease. The thermal conductivity of the carbon nano paste is measured experimentally. It is found that the thermal conductivity of the nano paste is enhanced up to 15.8% compared to the original paste, and the temperature of the LED chip is cooled down as low as 60.4℃, which is much lower than the temperature of 67.9℃ with the original paste.