As a renewable biomass resource, biochar is new to modify or replace asphalt binder in pavement engineering. This paper focuses on the effect of biochar on the anti-aging performance of asphalt binder. The short- and long-term aging properties of biochar modified asphalt binder were investigated using dynamic shear rheometer (DSR) and bending beam rheometer (BBR) tests. The modification mechanism was investigated through the Fourier-transform infrared spectroscopy (FTIR) test. The aging tests and viscosity analysis showed that the softening point of biochar modified asphalt binder was higher than base asphalt binder, while the aging index and aging viscosity ratio were lower than base asphalt binder. After aging, the temperature sensitivity of biochar modified asphalt binder decreased and the high-temperature stability, reflected by dynamic shear modulus and resistance to rutting, improved. The BBR test after long-term aging showed that the anti-aging performance of biochar modified asphalt binder decreased with the decrease in temperature, and control of the biochar content could ensure good low-temperature performance of the modified asphalt binder after aging. FTIR spectra analysis showed that biochar in modified asphalt binder is physically blended with asphalt binder.