[Purposes] This paper aims to explore the new type of warm mixing recycling agent of styreneic methyl copolymer (SMC) recycling effect and mechanism of aging styrene butadiene styrene (SBS) modified asphalt. [Methods] Firstly, the old asphalt with different aging degrees was prepared indoors. Secondly, a SMC recycling agent was used to regenerate the styrene butadiene styrene(SBS) modified asphalt with different aging degrees. Then, dynamic shear and flexural creep tests were carried out on SMC regenerated asphalt to evaluate its rheological properties. Finally, the mechanism was revealed by the Fourier transform infrared reflection test, and the SMC recycling effect was evaluated by the scanning electron microscope test. [Findings] The results show that the SMC recycling agent reduces the rutting index and the recovery rate of aging asphalt, furthermore, it significantly improves the low-temperature performance of aging asphalt. The SMC recycling agent and aging asphalt are physically blended without chemical reaction. Besides, SMC recycling agent can compensate the cracks caused by asphalt aging. [Conclusions] The SMC recycling agent has a better repair effect on aging asphalt, which can provide a new way for asphalt regeneration.