Continuous　fiber-reinforced　polyphthalazine　ether　sulfone　ketone　(PPESK)　thermoplastic　resin　matrix　composites　(CFRPs)　constitute　a　class　of　novel　composite　materials;　however,　their　wide-temperature-range　mechanical　properties,　in　particular,　the　interlaminar　interface　properties,　have　rarely　been　investigated　to　date.　Therefore,　in　this　study,　a　cross-scale　research　method　was　proposed,　which　established　a　mapping　system　among　macroscopic　interlayer　performance,　mesoscopic　local　damage,　and　microscopic　molecular　dynamic　(MD)　evolution.　The　interlaminar　performance　and　damage　mechanisms　of　CF/PPESK　at　different　temperatures　were　investigated　by　short　beam　shear　tests,　scanning　electron　microscopy,　and　numerical　simulations.　The　study　innovatively　constructed　a　mesoscopic　model　incorporating　interlaminar　and　fiber–matrix　interfaces,　delving　deeply　into　the　spatial　multi-regional　local　damage　characteristics　among　the　components　of　CFRPs.　At　the　microscopic　molecular　level,　MD　simulations　were　used　to　calculate　shear　viscosity,　which　was　further　used　to　quantify　the　micro-movement　capability　of　the　composite　resin　at　different　temperatures.　The　results　indicate　that,　owing　to　its　unique　twisted　non-coplanar　biphenyl　structure　and　resistance　to　damage　at　high　temperature,　PPESK　retains　its　resin　and　interface　micro-movement　adjustment　capabilities　even　at　extreme　temperature　(503　K),　allowing　it　to　fill　the　gaps　and　encapsulate　the　fibers,　thereby　providing　protection.　This　unique　＇damage　regulation　mechanism＇　significantly　enhances　the　damage　tolerance　of　PPESK　at　high　temperature.　Simultaneously,　the　spatial　multi-region　local　damage　characteristics　validated　the　hypothesis　that　the　interlaminar　performance　of　the　material　is　related　to　its　tensile　and　compressive　strengths.　The　stepwise　scaling　macro–meso–microscopic　cross-scale　numerical　simulation　method　has　opened　up　a　new　avenue　for　the　study　of　temperature　mechanism　of　thermoplastic　composites　and　even　thermosetting　composites.　©　2024　Elsevier　B.V.