The utility model discloses a mine compressed air self-rescue automatic drainage device which comprises a transverse rod, a floating ball, a drainage port, a conical head, a round bucket, a guide rod, an air inlet pipe and an air outlet pipe. The air inlet pipe and the air outlet pipe are respectively arranged on the upper portion of the round bucket, the air inlet pipe is connected to a high-pressure air pipe through a control valve, the air outlet pipe is connected to a compressed air self-rescue device, the drainage port is formed in the middle of the lower portion of the round bucket, the transverse rod is fixedly arranged at the upper end of the interior of the round bucket, the guide rod is fixedly connected to the lower portion of the middle of the transverse rod, the floating ball is arranged on the guide rod in a sleeved mode, the conical head is arranged at the lower end of the floating ball, and the conical head corresponds to the drainage port. Automatic drainage is achieved, potential safety hazards are eliminated, the safety factor of the compressed air self-rescue device is increased, and the mine compressed air self-rescue automatic drainage device has the advantages of being reasonable in structure, safe, reliable and the like.