The invention relates to an acrylonitrile device reaction gas cooler quick-cleaning method, which belongs to the technical field of acrylonitrile production, and is characterized by comprising the cleaning steps of removing propylene feeding of a reactor, stopping a heat removing water pump of the reactor, burning ammonia gas for 27min to 33min, rising the temperature of the reactor to 453 DEG C to 458 DEG C through improving the feeding amount of the ammonia gas, maintaining for 55min to 65min, and air purging the reactor so as to replace gas in the reactor; feeding nitrogen into the reactor,wherein the volume of the nitrogen amount entering the reactor under ordinary pressure is 2 to 4 times of the volume of a cooler; starting a water supply pump, independently cooling the cooler connected to the rear part of the reactor, and disassembling a seal head and adding a blind plate for carrying out water pressure cleaning on the cooler after the temperature of the cooler is reduced to theprocessing temperature required for acrylonitrile reaction. According to the cleaning method, the parking time is shortened to be 1/4 to 1/7 of the original parking time, and the single-pass yield ofacrylonitrile is more than 81 percent after driving.