The invention discloses an exhaust fan. The exhaust fan comprises a box and a volute fan. The box comprises a cover plate, a side plate and a bottom plate. A containing cavity is defined by the coverplate, the side plate and the bottom plate. The volute fan comprises a volute, a wind wheel and a motor, and the volute is fixed in the containing cavity of the box and comprises a front end plate, arear end plate and a side panel, wherein a cavity is defined by the front end plate, the rear end plate and the side panel, and the wind wheel is arranged in the cavity. The cover plate is provided with a gap, and an opening is formed in the side plate. The front end plate is provided with a first air inlet. The side panel is provided with an air outlet. The gap, the first air inlet, the cavity, the air outlet and the opening are in communication so that a first ventilation channel can be formed. The rear end plate is provided with a second air inlet. An air flue is formed between the side plate and the side panel. A runner is formed between the rear end plate and the bottom plate. The gap, the air flue, the runner, the second air inlet, the cavity, the air outlet and the opening are in communication so that a second ventilation channel can be formed, one ventilation channel is additionally arranged, the air inlet area is increased, efficiency is improved, and noise is improved.