With　the　increasing　frequency　and　severity　of　extreme　disaster　events,　enhancing　the　resilience　of　urban　power　grids　has　become　critical.　Most　studies　focus　on　distribution　networks　(DNs)　without　considering　the　important　coupling　relationship　between　transportation　networks　(TNs)　and　DNs.　This　paper　addresses　this　gap　by　proposing　a　tri-stage　resilience　improvement　method　for　power-transportation　coupled　networks　(PTNs),　incorporating　flexible　resources.　The　approach　includes　three　models:　(1)　a　pre-allocation　model　with　a　line　hardening　strategy　based　on　vulnerability　index　for　defense,　(2)　a　failure　response　model　that　analyzes　the　impact　of　typhoons　on　PTN　and　minimizes　load　reduction　in　the　DN,　and　(3)　a　restoration　model　that　integrates　emergency　repair　crews　and　mobile　energy　storage,　optimized　via　linear　programming.　The　performance　of　the　proposed　method　is　evaluated　using　a　PTN　with　the　IEEE　33-bus　distribution　test　system　and　its　corresponding　TN.　Results　demonstrate　that　the　resilience　of　PTN　can　be　enhanced　effectively　by　applying　the　proposed　tri-stage　method.