Abstract: Artificial accelerated weathering test on thermoplastic elastomer SBS was conducted by using a fluorescent UV/condensation weathering device. The changes in surface color, morphology, structure and mechanical properties were monitored by spectrometer, microscope, Fourier transform infrared spectroscopy and tensile testing machine. The results showed that the surface color of SBS turned to yellow with increasing aging time, and the cracks became dense gradually. Carbonyl (>C=O) group was observed from ATR FTIR spectrum. The elongation at break, tensile stress at break and tear strength decreased quickly in the initial stage of aging procedure and then stabilized, while the Shore A hardness increased with the increase of aging time. The mechanical properties turned to be hard and brickle with the evolvement of aging. The change of elongation at break can be used to detect the degradation of SBS.