Abstract: The present invention proposes a smart circuit device of a smoke exhauster for cooking. The smart circuit device of the present invention comprises a sensing circuit comprising a temperature sensor and a smoke sensor, a signal processing circuit of temperature sensor, a signal processing circuit of supersonic transducer, a microprocessor control circuit, an output and display circuit, a motor-driving circuit, and a power circuit. The temperature sensor is used to assist the smoke sensor (supersonic transducer). The present invention can detect the variations of the quantity of smoke and temperature in the cooking environment as input parameters to the microprocessor control circuit. The microprocessor control circuit will operate according to the fuzzy control theory to control the motor of the smoke exhauster to operate at a proper rotation speed so as to reduce noise, save energy, and achieve the object of automatic control.