In order to reduce the weight and production cost of light emitting diode (LED) lamps, a special-shaped LED lamp without radiator is designed based on the principle of the chimney effect. A three-dimensional model is built by Solidworks software, and its plug-in called Flow Simulation is used to simulate the model. Based on the model that the height of chimney is 30 mm and diameter of chimney is 20 mm, the influences of different heights and diameters of chimney on the highest temperature of the special-shaped LED lamp are studied. Simulation results show that for the special-shaped LED lamp with the chimney height of 45 mm, chimeney diameter of 45 mm and substrate weight of 35.86 g. The highest temperatures of the LED are all lower than security junction temperature of 85 ℃, when the input powers are 6,8,10 W, which meets the security requirements. The experiment of special-shaped LED lamp with the power of 8 W is carried out. The result shows that the highest temperature of the special-shaped LED lamp is 73 ℃, which is only 2.06 ℃ higher than the simulation results. It confirms the correctness of the simulation. In conclusion, this special-shaped LED lamp without radiator not only has the ability to well satisfy the heat dissipation requirements of LED, but also has the light weight, a low cost and a simple manufacturing process.