Abstract: In the service process of asphalt pavement, high temperature environment and water may accelerate the aging of asphalt. The main purpose of this research is to reveal the aging performance of SBS modified asphalt under a high-temperature condition and rainy environment along with the aging mechanism. A moisture-thermal coupling environment was developed to simulate the aging process of SBS modified asphalt. Asphalt was first conducted to Rolling Thin Film Oven（RTFOF） test, and then Pressurized Aging Vessel（PAV） test was carried out. Based on these aging procedures, the asphalt was put at the temperature of 80℃ for 24 hours. The high-temperature rheological test and Infrared Spectroscopy（IR） test were carried out on the treated asphalt and SBS modified asphalt under different aging conditions（i.e., un-aged, short-term aged, long-term aged）. According to the change of rheological properties and functional groups, the effect of moisture-thermal coupling on the aging property of the SBS modified asphalt was evaluated and the mechanism was also explained. The test results showed that among the four SBS modified asphalt, the asphalt with the treatment of high-temperature water bath has the maximum complex modulus and the minimum phase angle. Under the combination effect of high temperature and water environment, the thermal oxidative aging of SBS modified asphalt is further aggravated. Additionally, the growth law of complex modulus at different aging stages is consistent with that of sulfoxide and carbonyl groups in SBS modified asphalt. At the same temperature, the presence of water will accelerate the aging of SBS asphalt.