Introduction　Steel　building　is　a　form　of　construction.　Non-intumescent　fireproofing　materials　have　superior　fireproofing　effects　and　can　provide　effective　fireproofing　and　thermal　insulation　protection　for　steel　structures.　However,　the　modification　and　innovation　of　non-intumescent　fireproofing　materials　are　insufficient　in　China　at　present.　Seafoam　has　a　good　thermal　stability　and　a　low　thermal　conductivity,　having　a　thermal　insulation　effect,　which　can　be　used　as　a　filler　for　fireproof　coating　or　fireproof　board.　Seafoam　can　effectively　improve　the　fire　resistance　of　fireproof　coating　or　fireproof　board.　Seafoam　mineral　fibers　dispersed　in　a　low　concentration　solution　can　form　a　stable　high-viscosity　suspension,　so　they　can　be　dispersed　and　modified　with　other　fillers　and　added　to　fireproof　coating　or　fireproof　board　slurry.　Therefore,　the　fire　performance　of　seafoam　fiber　fireproofing　materials　can　be　improved.　In　this　work,　a　modified　seafoam　fiber　was　added　to　fireproof　coatings　for　improving　the　fire　performance　of　non-intumescent　fireproof　coatings.　This　modified　fiber　as　a　kind　of　modified　fiber　was　prepared　via　mixing　seafoam　fiber,　magnesium　hydroxide　fiber　and　silicon　oxide　fiber　under　high-speed　mixing　and　adding　polymer　modifier.　In　addition,　the　physical　and　chemical　properties　and　fire　performance　of　the　finished　product　were　also　analyzed.　Methods　In　this　work,　5–70　mm　hydromagnesite　fibers　were　ground　in　a　mill　to　obtain　the　fibers　with　the　lengths　of　©　2025　Chinese　Ceramic　Society.　All　rights　reserved.