Abstract: Thermal design of air convection for an LED lamp was carried out. The simulations for the lamp with or without air convection were studied. In order to ensure the accuracy of simulation result, the thermal analysis model was modified repeatedly. The simulation and test results show that the junction temperature of the LED lamp reduces by about 8℃ with air diversion cooling, the lifetime of the LED lamp can extend by 2 000 hours. Further study shows that many factors affect the heat radiation apparently, such as the emissivity of base plate subsurface, the thermal contact resistance, and the distance between convection hole and LED. Sensitivity analysis for each factor was carried out, and some advices on how to further reduce the junction temperature of the LED lamp were put forward.