Lignin fiber is an organic fiber obtained from natural wood through chemical treatment, possessing excellent qualities such as being non-toxic, odorless, and pollution-free. Its microstructure is ribbon-like, curved, uneven, and porous, with flattened intersections. It exhibits good toughness, dispersibility, and chemical stability, strong water absorption capacity, and outstanding thickening and crack resistance properties. As a stabilizer for SMA, it improves the performance of asphalt mixtures, adsorbs asphalt, reduces leakage, and serves multiple functions such as reinforcement, dispersion, and viscosity enhancement.