To　solve　the　poor　fireproof　performance　of　plant　fibers,　one　of　the　technical　difficulties,　and　use　more　straw　fibers　as　construction　materials,　wheat　straw　fibers　(WSFs)　have　been　subject　to　flame-retardant　modification.　Then,　tests　and　analysis　over　the　modified　WSFs　per　the　burning　behavior　and　pyrolysis　performance　have　been　made.　The　physical　and　mechanical,　and　thermal　insulation　properties　of　wheat　straw　fiber　cement-based　composites　(WSFCC)　at　high　temperatures　were　characterized.　The　results　are　as　follows:　Ammonium　polyphosphate　(APP),　magnesium　hydroxide　(MH),　and　aluminum　hydroxide　(ATH),　three　fire　retardants,　all　affect　the　chemical　structure　of　WSFs.　P,　Mg,　and　Al　elements　of　the　three　retardants　are　successfully　adsorbed　onto　the　fibers＇　surface　subject　to　modification.　Flame-retardant　WSFs　significantly　outperforms　the　non-flame-retardant　ones　per　thermostability　and　flame　retardancy.　The　heat　release　rate　(HRR),　total　heat　release　(THR),　effective　heat　of　combustion　(EHC),　and　mass　loss　rate　(MLR)　of　most　flame-retardant　WSFs　are　obviously　lower　than　those　of　non-flame-retardant　ones.　The　APP-modified　WSFs　demonstrate　higher　total　smoke　production　(TSP),　while　WSFs　modified　with　composite　flame　retardants　perform　better　in　flame　retardancy　and　smoke　suppression.　The　MLR　of　WSFCC　at　high-temperature　increases　as　the　temperature　goes　higher.　The　compressive　and　flexural　strengths　of　WSFCC　decrease　with　the　increase　of　temperature　and　the　decrease　mitigates　after　350　degrees　C.　In　terms　of　thermal　conductivity,　composite-flame-retardant　fiber　WSFCC　are　much　higher　than　non-flame-retardant　fiber　and　APP-modified　fiber　WSFCC.　As　the　temperature　rises,　the　thermal　conductivity　of　composite-flame-retardant　fiber　WSFCC　tends　to　decrease.　(C)　2021　The　Authors.　Published　by　Elsevier　B.V.