The invention discloses an extractor hood with automatically controlled gears. The extractor hood with automatically controlled gears is characterized by comprising an exhaust fume collecting hood body, a control system, an exhaust fume probe, a temperature sensor and a motor, wherein the exhaust fume probe and the temperature sensor are installed on the exhaust fume collecting hood; and the control system changes the rotation speed of the motor according to signals fed back from the exhaust fume probe and the temperature sensor. The generation and escape conditions of exhaust fume can be accurately mastered, the gears and air volume of the extractor hood can be automatically controlled along with change of the concentration of the exhaust fume, the both hands of people are liberated, the intelligence degree is high, and the exhaust fume extraction effect is good. Meanwhile, the air volume of the extractor hood is changed along with change of the exhaust fume amount, pollution of the exhaust fume to the exhaust fume probe is effectively reduced, the service life of the exhaust fume probe is prolonged, and the pursuit of customers for environment protection, noise reduction, energy conservation and intelligence is met.