Downhole dustproof mask

The utility model provides an underground dustproof mask which comprises a mask body, an air constant temperature system and an air inlet pipe used for connecting an air outlet of the air constant temperature system and an air inlet of the mask body. A breathing box with a one-way exhalation valve is arranged on the front side of the mask main body; the one-way exhalation valve comprises a sleeve arranged on the front side of the breathing box, a sealing shell arranged in an inner cavity of the sleeve and a sealing piece arranged in the sealing shell. One end of the sealing piece is hinged to the sealing shell, and the other end is attached to the sealing shell. According to the dustproof mask, one end of the sealing piece is hinged to the sealing shell, the other end of the sealing piece is arranged to be the free end, and a user can easily exhaust waste gas; the air constant-temperature system is arranged, meanwhile, the air constant-temperature system directly supplies air to the mask body, an appropriate