The invention discloses a device capable of automatically shutting off a power supply and an air port of a double-stay type exhaust fan in a co-delaying manner. A shut-on volumetric apparatus is suspended on a shut-on line of the exhaust fan; a shut-off volumetric apparatus is suspended on a shut-off line of the exhaust fan; one end of a corrugated water guide tube is arranged on a water leaking tube at the bottom of the shut-on volumetric apparatus in a sleeved manner; the other end of the corrugated water guide tube is inserted into the shut-off volumetric apparatus; and a flow speed regulator is arranged on certain section of the corrugated guide tube. After the device is shut on, water in the shut-on volumetric apparatus drops into the shut-off volumetric apparatus through the corrugated water guide tube; after certain time, gravity of dropped water overcomes resistance to pull down the shut-off line to realize automatic shut-off. Delayed duration for automatically shutting off is estimated according to the formula [(t+T)/2]k. The device can be used for manufacturing a novel exhaust fan, and also can be used for improving the original exhaust fan in a suspending manner. The novel exhaust fan can be used for life, and also can be used for teaching as an innovation-type scientific training aid due to the fact that the novel exhaust fan is very matched with teaching content Water Consumption Measuring time in Science of the primary school.