Ventilation fan

The utility model relates to an indoor and outdoor air exchanger, in particular to an exhaust fan, in which a power switch and a shutter are linked for opening and closing. The exhaust fan is composed of a shell, a motor and fan blades; the shutter is arranged on the wind outlet surface of the shell; the exhaust fan further comprises a link bar to push the on-and-off of the power switch; the power switch is connected in series with the operating circuit of the motor; and one end of the link bar is movably linked with the shutter. The indoor and outdoor air exchanger has the advantages that (1) exhaust is started when the link bar is pulled, at the same time the link bar pulls the shutter to open, thereby effectively improving the exhaustion capability; and (2) the exhaust is stopped, a reset spring pulls the link bar upwards, and the shutter is closed and difficult to open by wind under the action of the spring normally.