Dry gas seal device of long defeated pipeline natural gas compressor. The periphery of rotation axis by the medium incline that the atmospheric side has arranged one in proper order, second grade end face seal unit and keep apart sealing unit, still the polyphone has maze sealing unit between two -stage sealing unit. Have respectively in the two -stage end face seal unit with relative movable sealing ring who sets up of axle head and static seal ring, be the end face seal position between its relative terminal surface, the labyrinth seals unit is in the gas passage at the end face seal position of intercommunication two -stage end face seal unit, sets up the comb tooth structure body that having of in gas passage facing wall interfacial stretch the apex end and seal structure layer that can with it little clearance fit respectively, have axial positioning's broach ring seat and locate its radial inboard broach ring in keeping apart sealing unit, broach top that the broach intra -annular directly inclined with can be along with axis of rotation's the rotator outer face of cylinder with radial relative setting the in close clearance. Special operating mode and the environment that gas seal device can adapt to long defeated pipeline natural gas system should be done, the sealed reliable stable comprehensive properties of its compressor dry gas was effectively promoted.