Poly(p-phenylene-benzimidazole-terephthalamide)　(PBIA)　fibers,　a　kind　of　heterocyclic　aramid　fibers,　possess　extraordinary　mechanical　properties　and　advanced　applications　in　aerospace,　military　protection,　and　other　civilian　areas.　However,　harsh　application　scenarios　are　putting　forward　even　stringent　requirements　for　the　mechanical　performances　and　environmental　compatibility　of　PBIA　fibers.　Strengthening　lateral　interactions　between　polymer　chains　are　approachable　methods　but　ongoing　challenges　to　obtain　PBIA　fibers　with　high-performance.　This　work　develops　a　novel　holey　reduced-graphene-oxide　(HrGO)/PBIA　composite　fiber　with　a　scaffolded　structure,　in　which　the　HrGO　plays　a　role　of　clamp　to　effectively　band　plentiful　PBIA　chains　through　the　in-plane　holes.　A　small　amount　of　HrGO　(0.075　wt%)　is　able　to　improve　the　tensile　strength　and　Young＇s　modulus　of　HrGO/PBIA　fibers　by　11.5%　and　8.3%,　respectively.　The　small　amount　of　well　dispersed　HrGO　improves　the　crystallinity　and　serves　as　the　topological　constraint　that　enhances　the　lateral　interaction　of　the　PBIA　chains,　which　is　unveiled　by　the　wide-angle　X-ray　scattering　and　the　coarse-grained　molecular　dynamics　simulations.　In　addition,　the　favorable　compatibility　of　HrGO/PBIA　fibers　in　complex　application　scenarios　is　demonstrated　by　the　dynamic　and　cyclic-loading　measurements.