The invention relates an insulating coating which comprises the following components: cellulose acetate fiber resin, active methyl-containing polyurethane resin, ethylene glycol dimethyl ester, phenol propane epoxy resin, polyamide resin, elastic polyurethane emulsion, water-based silicone acrylic emulsion, hydroxypropyl methyl cellulose, calcined kaolin, talcum powder, phthalo blue, 1250-mesh barium sulfate, carbon black, butyl cellosolve, m-nitrophenol, ammonium polyphosphate, pentaerythritol, arene sulfonic acid, a silane coupling agent, a flatting agent, a sterilization preservative and a solvent. The insulating coating has the following beneficial effects that the mechanical strength is high, the weather fastness is good, the adhesion force is good, the acid resistance is good, the service life is long, and above all, the insulating coating can be used for a long time at a high temperature of 260-360 DEG C.