In order to improve the cooling capacity of light emitting diode (LED), based on the principle of the chimney effect, the cylinder is added to traditional sunflower radiator to form a special chimney structure. We build a three-dimensional model by adopting Solidworks, and use its plug called Flow Simulation to simulate the model. The model with the number of fins of 12, the maximum diameter of 70 mm and the hight of radiator of 40 mm is optimized. Studies have shown when the number of fins is 20, the maximum diameter is 85 mm and the hight of radiator is 65 mm, LED cylindric sunflower radiator have the best cooling capacity. At the moment, the optimized highest temperature of LED is 48.98 ℃, which is reduced by 13.05 ℃. The temperature of the LED can meet the security requirements when the power of the LED chips are 8, 12, 16, 19 W. The LED radiator sample with the power of 8 W is experimentally tested. The results show that the average error between the actual temperature of the 4 monitoring points and the simulated temperature is 4.8%, which is within the allowable range. It confirms the correctness of the simulation steps. When the power is 32 W, the highest temperature of the LED chips still meet the technical requirements of less than 125 ℃. Which is 6.44 ℃ lower than that of the traditional sunflower radiator. In conclusion, the designed LED cylindric sunflower radiator can provide a new way to solve the heat dissipation problem of high power LED.