Abstract: In order to prevent the personnel casualties caused by the traditional flame proof door flying from the mine shaft mouth when a underground mine explos ion made, a series products of the automatic resetting type flame proof door of the mine ventilation shaft were researched and developed. The paper introduced the air | eakage measures, proposed that the blade strength of the fan was applied to calculate the explosion impact load on the flame proof door. Thus the formula of the conne ction part strength between the beam (column) and the door plate and beam (column) of the flame proof door and the formula of the door plate thickness set with the ne gative pressure of the ventilation shaft were provided.The automatic resetting type flame proof door of the mine ventilation shaft was reliably sealed in normal time.Whe n the mine ventilation stopped, the door would be automatically opened for natural ventilation.When the mine ventilation reset, the door would be automatically closed. When a explosion occurred, the protection for the main ventilators would be rapidly opened.When the explosion passed, the door would be automatically reset and the mine ventilation system would rapidly recovered.Thus a powerful condition would be created for the self rescue and emergency rescue of the refuges.