Abstract: As a critical component of automobile, accurate lifetime assessment of light emitting diode (LED) headlamps is essential for ensuring driving safety. To address the challenge of prolonged test period for LED lifespan, a temperature-humidity accelerated life test on a specific automotive lamp module is conducted in this paper. Aging tests are conducted at the ambient temperatures of 65 ℃, 75 ℃, and 85 ℃ respectively, with a relative humidity of 85%. Lifetime data corresponding to the luminous flux decaying to 70% threshold of origin value is measured, which is used for reliability modeling using the Weibull distribution. Based on the Peck model, a mean activation energy of 8.7623×10⁻²⁰ J is obtained for the module. A lifetime prediction model in consideration of LED junction temperature and humidity is established. Furthermore, the model is used to evaluate the lifetime enhancement of LED module achieved by introducing a vapor chamber-based phase-change heat sink for thermal management. Results show that a maximum lifespan improvement of up to 37.85% is achieved. This study provides references for the lifetime assessment and prediction of LED headlamp modules.