The invention relates to an online and rapid leakage detecting method for a roller hearth type non-oxidation furnace radiating pipe. A sealing gasket and an explosion preventing sheet are manufactured according to the size of a flange in the connecting position of a burning nozzle body and a waste gas pipe; a single burning nozzle is closed, a burning nozzle waste gas pipe is disassembled, the sealing gasket and the explosion preventing sheet are installed between a burning nozzle flange and a waste gas pipe flange, and a bolt is tightly screwed; a gas pipeline pressure detecting hole or a combustion-supporting air pipeline pressure detecting hole is opened, and a pressure gage is connected; a combustion-supporting air pipeline is disconnected from a black rubber pipe, nitrogen is injected into a combustion-supporting air pipe, and the pressure of the pipeline is maintained at 6+/-0.5KPa, the nitrogen injection stops, and the seal of an injecting opening is maintained; that whether a numerical value of the pressure gage is different from a pressure value shown when the nitrogen injection stops or not is observed after two or three minutes; and if the pressure is reduced, the radiating pipe is proved to have a leakage point. The invention can carry out effective, convenient and rapid leakage detection on the roller hearth type non-oxidation furnace radiating pipe and synchronously carry out leakage detection during normal production.