The invention discloses a self-learning automatic noise reduction system and method of a kitchen ventilator. The system mainly comprises a flue gas turbine, a microphone and a loudspeaker are arranged on the flue gas turbine, after the flue gas turbine is assembled, and before the turbine leaves the factory, the turbine is subject to primary pre-alignment, and the pre-alignment data serve as following field actual running preset benchmark data, and after the flue gas turbine is mounted at the user home, the flue gas turbine runs at the different rotating speeds; flue gas turbine noise and environment noise at different rotating speed segments are collected through the microphone, collected measured data are fed back to a signal processing module on the glue gas turbine, and a self-learning noise reduction algorithm module is combined with the measured data of the flue gas turbine noise and the environment noise to generate a corresponding sound waveform according to the benchmark data preset in a pre-alignment module; the sound waveform is output through the loudspeaker and is used for offsetting most part of noise. The system has the beneficial effects that the main noise component can be effectively removed, a certain obvious effect is achieved, a corresponding sound field and a complex algorithm do not need to be built, and meanwhile, expensive hardware circuit supporting does not need to be built.