High-rise　building　fires　can　be　characterized　by　a　rapid　spreading　and　are　challenging　to　extinguish.　The　chimney　effect　of　cable　shafts　in　high-rise　buildings　will　greatly　increase　the　spread　speed　of　fire　and　smoke,　and　will　also　make　it　harder　to　put　out　fires.　Therefore,　fire-blocking　materials　or　fire　protection　measures　are　usually　used　in　cable　shafts　to　slow　down　or　even　block　the　spread　of　fire.　Currently,　most　of　the　research　focuses　on　the　fire　performance　of　fire　protection　materials,　and　there　are　relatively　few　studies　on　the　impact　of　fire-blocking　materials　on　the　operation　state　of　cables.　Based　on　the　theories　of　electromagnetism,　fluid　mechanics,　and　thermodynamics,　the　paper　establishes　a　multiphysics　simulation　model　of　a　double-layer　cable　shaft.　Then,　the　electromagnetic-fluid-temperature　distribution　in　the　cable　shaft　under　rated　operating　conditions　is　analyzed,　and　the　influence　of　the　fire-blocking　material　is　discussed.　The　simulation　results　show　that　the　firestop　material　will　affect　the　heat　dissipation　of　the　cable,　which　causes　the　hot-spot　temperature　of　the　cable　to　slightly　increase　by　1　to　2°C,　and　the　relative　growth　rate　of　its　hot-spot　temperature　rise　is　close　to　6.83%.　©　2023　Bo　Qu　et　al.