Abstract: Urumqi petrochemical Co.,CNPC adopts the online decoking technology for its 1.2 Mt/a delayed coking device. This text introduces the situation of heating furnace. The online decoking technology prolongs the furnace running time, but has some adverse effect on the heating furnace, such as thermocouple falling off, tube surface oxidation peeling, tube entrance capebolt loosing，heating furnace outlet flange bolt fatigue. Some suggestions are proposed to solve these damages.