Fe-based　amorphous　coatings　have　been　proposed　to　perform　a　promising　thermal　barrier　application,　however,　the　uncertain　degeneration　of　properties　induced　by　thermal　stimulation　is　significantly　concerned　owing　to　their　metastable　nature.　Herein,　Fe57Cr15Nb4B20Si4　amorphous　coating　with　a　low　thermal　conductivity　was　employed　to　investigate　the　degeneration　of　thermal　insulation　property　and　related　mechanisms　during　long-term　heat　exposure.　Excellent　stability　can　be　defined　for　the　amorphous　coating　when　annealed　below　glass　transition　temperature,　despite　a　slight　increase　of　thermal　conductivity　induced　by　structural　relaxation.　Extraordinary　increase　of　thermal　conductivity　is　found　when　prolonged　annealing　time　at　a　critical　temperature　of　600　°C.　The　sluggish　structural　sintering　dominates　thermal　conductivity　to　increase,　whereas　the　effect　of　precipitated　ultrafine　nanocrystals　is　little.　The　cooperation　of　grain　coarsening　and　structural　sintering　leads　to　a　dramatical　increase　of　thermal　conductivity　at　the　initial　stage　of　850　°C　annealing,　while　the　relatively　low　increase　of　thermal　conductivity　with　prolonged　duration　is　ascribed　to　the　further　grain　growth.　The　obtained　results　demonstrate　a　comprehensive　understanding　on　the　thermal　evolution　of　Fe-based　amorphous　coatings　and　form　a　basis　for　future　works　aiming　to　shed　further　light　on　the　degeneration　of　related　metallic　coatings　at　high　temperatures.　©　2023