The invention relates to an oil fume exhaust ventilator and a control method thereof. The control method comprises: S1, in an electrifying standby state of an oil fume exhaust ventilator, real-timely detecting the temperature of a detection region below the oil fume exhaust ventilator; S2, based on whether the detected temperature achieves the startup condition, and if yes, performing a step S3; S3, opening a fan, and in the fan opening state, real-timely detecting the temperature of the detection region below the oil fume exhaust ventilator; S4, based on whether the detected temperature achieves the shutdown condition, and if yes, performing a step S5 and if no, adjusting the size of the fan wind screen according to the temperature change; and S5, closing the fan. According to the control method of the present invention, the temperature of the detection region below the oil fume exhaust ventilator is detected, and the startup, the shutdown, and the size of the fan wind screen of the oil fume exhaust ventilator are subjected to linkage control according to the temperature, such that the accurate control on the oil fume exhaust ventilator according to the condition of the oil fume produced by the cooker is achieved so as to reduce the unnecessary waste of resources and achieve the effects of energy saving and environmental protection.