The invention discloses a plasma reaction cavity cleaning device, which comprises multiple gas input pipes penetrating the wall of a plasma reaction cavity at intervals; included angles are formed between extending parts of the gas input pipes and the side wall of the plasma reaction cavity; and a quick regulation valve can be arranged at each gas input pipe to control gas flow inputted into the reaction cavity. A plasma reaction cavity cleaning method comprises the steps of inputting gases with cleaning capabilities into the reaction cavity by a gas nozzle; inputting gases into the reaction cavity by the plasma reaction cavity cleaning device, and enabling the gases to be subjected to ionization to form plasma; continuously inputting gases into the reaction cavity by the plasma reaction cavity cleaning device and stirring the plasma to form vortex; and enabling the plasma vortex to react with deposited polymers in the reaction cavity through violent moving, and discharging the gases after the cleaning is finished. According to the invention, the plasma can be enabled to form violent moving, and the reaction probability of the plasma and the deposited polymers at hard-to-clean positions can be improved, so the cleaning capability for the deposited polymers at the hard-to-clean positions can be improved.