［Purposes ］ This study aims to investigate the effects of lignin fibers and basalt fibers with different lengths on the properties of asphalt mastics.［Methods］ The high -temperature deformation resistance of fiber -reinforced asphalt mastics was evaluated using a dynamic shear rheometer （DSR），while low -temperature crack resistance was assessed with a bending beam rheometer （BBR）.A fluorescence microscope （FM） and scanning electron microscope （SEM） were employed to characterize fiber surface morphology and interfacial bonding of asphalt mastics.［Findings］ Asphalt mastics reinforced with 6 mm basalt fibers exhibit a higher rutting factor，lower phase angle，and reduced average irrecoverable creep compliance.Additionally，the creep stiffness modulus of asphalt mastics reinforced with lignin fibers is minimized，while the slope of the creep curve reaches its maximum.Microscopic observations reveal that basalt fibers are interlocked to form a dense structure in the mastic system.Lignin fibers featured rough surfaces capable of adsorbing substantial amounts of asphalt.［Conclusions ］ Asphalt mastics incorporating 6 mm basalt fibers demonstrate superior high -temperature deformation resistance，while lignin fiber -reinforced basalt mastics exhibit better low -temperature crack resistance.These findings offer valuable insights for practical engineering applications.