The invention discloses a high-temperature flue gas fast cooler. The high-temperature flue gas fast cooler comprises a shell, air cooling boxes, a cooling tower and a bent pipe. The air cooling boxes are arranged inside the shell. The bent pipe is arranged inside the cooling tower. The shell, the air cooling boxes and the cooling tower are all of a rectangular box-shaped structure. The shell is arranged at the left side of the cooling tower. A flue gas inlet is formed in the upper right corner of the shell, and a flue gas outlet is formed in the lower left corner of the shell. According to the high-temperature flue gas fast cooler, each air cooling pipe is in a rectangular box shape, the contact area between the air cooling pipes and high-temperature flue gas in the shell is large, the cold and heat exchange rate is high after water is connected into the air cooling pipes, and the cooling effect is good; and heat emitted from the pipeline wall can be discharged out of the cooling tower in time through a fan and radiating holes, the water cooling effect can be achieved without arranging a long bent pipe, materials are saved, manufacturing cost is low, high-temperature water can be cooled to a low temperature, the efficiency for circulating cooling of the high-temperature flue gas next time is improved, and the high-temperature flue gas fast cooler is suitable for being popularized.