The invention discloses a dry gas sealing device of a long-distance pipeline natural gas compressor. A first-grade end surface sealing unit, a second-grade end surface sealing unit and an isolation sealing unit are arranged at the outer periphery of a rotating shaft in sequence from a medium side to an atmosphere side; and a labyrinth sealing unit is serially connected between the two stages of sealing units. Dynamic sealing rings and static sealing rings oppositely arranged with the shaft ends are respectively arranged in the two grades of end surface sealing units; end surface sealing parts are between the opposite end surfaces; the labyrinth sealing unit is a comb tooth structural body with a projection top end and a sealing structure layer in small clearance fit with the comb tooth structural body, which are respectively arranged between opposite wall surfaces in a gas channel for communicating end surface sealing parts of the two grades of end surface sealing units; the isolation sealing unit is provided with an axially positioned comb tooth ring base and a comb tooth ring arranged on the radial inner side; and a comb tooth top end on the inner diameter side of the comb tooth ring and a rotating body outer cylinder surface capable of rotating along with the rotating shaft are oppositely arranged in the radial direction by small gap. The dry gas sealing device can adapt to special working conditions and environments of a long-distance pipeline natural gas system, and effectively improves reliable and stable comprehensive performances of dry gas sealing of the compressor.