In this study, polydopamine/polyethyleneimine (PDA/PEI) bionic coating and nano-silica were self-assembled on the surface of polyacrylonitrile (PAN) fiber to construct bionic multilevel hierarchical structures. The fiber composites were in turn used as secondary modifiers to prepare fiber reinforced styrene butadiene styrene modified asphalt binder (SBS@M-AB). Field emission scanning electron microscopy, energy dispersive spectroscopy, and atomic force microscopy analyses revealed rough surface of the modified fiber and successfully constructed a biomimetic multi-level hierarchical structure. These intriguing aspects are conducive to mitigating the local high stress of SBS@M-AB and achieving multi-scale mitigation of stress concentration, which in turn improves the performance of Mud-brick PAN fiber (MB-PAN) incorporated SBS@M-AB. Dynamic shear rheometer test showed that MB-PAN/SBS@M-AB exhibited better viscoelastic properties and deformation resistance than the pristine PAN/SBS@M-AB. TG test showed that the bionic multi-level hierarchical structure enhanced the interfacial properties of fiber materials which in turn boosted the thermal stability of MB-PAN/SBS@M-AB. The cone penetration analysis showed the much higher shear strength of MB-PAN/SBS@M-AB than the pristime SBS@M-AB. The results of this study are promising and challenging for designing modified asphalts with better thermal and mechanical performance for practical applications in construction and highway industries.