A novel tubular oscillating heat pipe (OHP) with sintered copper particles (SCPs) inside a flat-plate evaporator for the thermal management of high-power LED chips was designed and fabricated. The thermal performance of designed OHP, temperature distribution and illumination profiles of LED array were experimentally tested and evaluated. Results showed that the addition of SCPs on the evaporator of OHP can facilitate the startup and make oscillating motions of liquid-plugs/vapor-bubbles inside copper tubes more easily. A lowest thermal resistance of 0.168 K/W was achieved by the OHP with SCPs when the input power to the LED array was 60 W, and the corresponding maximum LED temperature can be controlled below 70 degrees C. The temperature distribution of LED array at different inclination angles was almost coincident and achieved good uniformity if the designed OHP was operated at low filling ratios, indicating that the gravity action can be partially neglected. It was also found that the temperature of LED array was inversely proportional to the illumination intensity, and a high filling ratio can cause the degradation of illumination intensity of LED chips. A low filling ratio of 30% was preferred for the designed OHP applied in high-power LED cooling.