The invention discloses a three-way catalytic converter cooling system which comprises a nozzle, a temperature sensor and a vehicle-mounted computer, wherein the temperature sensor is fixed to a three-way catalytic converter and is connected to the vehicle-mounted computer; the nozzle is communicated with and is fixedly provided with a nozzle pipe; the nozzle pipe is slidingly connected with an exhaust pipe of an automobile; the top of the nozzle pipe is communicated with an air inlet pipe of the three-way catalytic converter; the nozzle pipe is slidingly connected with the air inlet pipe; the outer diameter of the nozzle pipe, the inner diameter of the air inlet pipe of the three-way catalytic converter, and the inner diameter of the exhaust pipe are equal; a nozzle end of the air inlet pipe is communicated with a tapered cavity; an opening is formed in the bottom of the tapered cavity and faces towards the exhaust pipe; an air cylinder is fixed to the outer wall of the exhaust pipe; the free end of the air cylinder is fixed to the outer wall of the nozzle pipe; and the air cylinder is connected to the vehicle-mounted computer. The three-way catalytic converter cooling system achieves the purpose of taking tail gas of the automobile as power to suck air to cool the excessively high temperature three-way catalytic converter, and a situation that the three-way catalytic converter can continue to work normally in a cooling process is ensured.