LEDs shipped to use in headlamps are forecasted to grow significantly from 10 million units in 2012 to 78 million units in 2018. The quality, lifetime and reliability requirements in the automotive sector are very high, higher than in most of the other LED sectors. The LED chip junction temperature is a critical factor which restricts the LED light source to be used in the automotive headlight. The power of the modern LED chip for light is above 1-5W, and the bottom heat transfer area of the chip die is less than 1 mm2, corresponding to 100-300 W/cm2 of heat flux, which will result in high chip junction temperature. The high junction temperature will greatly lead to the dominant luminescence wavelength drift, the decline of the optical efficiency, as well as the degradation the lifetime of LED. The ability to thermally manage and reduce the chip junction temperature has become paramount in the overall development of LED automotive headlight. Thermal resistance is a major indicator to evaluate heat transfer characteristics of an object. A combined thermal and photometric model for LEDs should be simulated by a suitable software.