The invention discloses an air cooling system for a three-way catalyst. The air cooling system for the three-way catalyst comprises a four-way pipe, a ventilating pipe, a turbocharger, a temperature sensor and an automobile-mounted computer, wherein the temperature sensor is fixed on the three-way catalyst and is connected to the automobile-mounted computer; the turbocharger comprises a turbine and an air compressor; one end of the four-way pipe communicates with an air inlet of the three-way catalyst; the rest three ends of the four-way pipe respectively communicate with an air outlet of the turbine, an air outlet of the air compressor and the ventilating pipe; the other end of the ventilating pipe communicates with one end of an electric three-way valve; the other two ends of the electric three-way valve respectively communicate with an exhaust pipe of an automobile and an air inlet of the turbine; and the electric three-way valve is connected to the automobile-mounted computer. The invention aims to provide the air cooling system for the three-way catalyst, automobile exhaust serves as power to extract air to cool down the three-way catalyst with over high temperature, and meanwhile, the three-way catalyst can continue working normally in a cooling process.