The invention relates to a rapid online disassembling device of a steel ladle upper nozzle, which belongs to the technical field of a steel ladle repairing tool, and is used for rapidly disassembling the steel ladle upper nozzle online. According to the technical scheme, the rapid online disassembling device comprises an air cooling push rod, a pull head, a pull rod, a hollow jack and a supporting frame, wherein one end of the air cooling push rod is connected with an air cooling device, the other end of the air cooling push rod is movably connected with the pull head, a large-diameter circular truncated cone on the rear part of the pull head is clamped at the outer side of the inner end surface of a steel ladle of the upper nozzle, the front part of the pull head penetrates through the upper nozzle in the steel ladle to be connected to the front end of the pull rod, the pull rod penetrates through the hollow jack, and the supporting frame is arranged between the bottom outer side of the steel ladle and the hollow jack. By adopting the rapid online disassembling device, the online disassembling of the steel ladle upper nozzle can be rapidly completed, the time for pulling out and replacing the upper nozzle can be shortened to 3 to 5 minutes, the working efficiency can be greatly improved, refractory on the bottom of the steel ladle can be prevented from being damaged, and the service life of the steel ladle can be prolonged. The rapid online disassembling device is scientific and reasonable in design, simple in structure, convenient to use and capable of solving the difficulty that the upper nozzle of the steel ladle cannot be replaced for a long time.