The vehicle elastomeric components such as engine mounts are aged and degraded by environmental loads during long term usage. These make the degradation of vehicle driving performance comparing with a new condition. In this study, the degradation of NVH (Noise, Vibration and Harshness) of used vehicles was analyzed. The main cause could be identified by the analysis of elastomers’ vibration insulation property changes. The properties changes of aged engine mounts were analyzed and compared with initial properties. The accelerated laboratory aging test mode was developed for simulating the degradation of engine mounts. Moreover, parametric study was carried out. The engineering design parameters of elastomers such as volume, thickness and loading types were identified to improve the thermal aging phenomenon.