An automatic resetting device for a spare anti-explosion well lid of a mining air well belongs to mining machinery and is mainly used for ensuring that the spare anti-explosion well lid can be automatically reset quickly after explosive blast of an anti-explosion well lid is released. The device is characterized by comprising a spare anti-explosion well lid trolley, a triggering mechanism, a sliding device and a guide rail. The spare anti-explosion well lid trolley is arranged on the guide rail, the triggering mechanism is in contact connection with the spare anti-explosion well lid trolley, and the sliding device is arranged on the guide rail. By means of the automatic resetting device, ventilation can be quickly restored, and a secondary disaster is reduced.