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　degrees　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　degrees　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.