The utility model discloses a drum-type dry-process methane fermentation tank sealing device which includes a feeding barrel (1) and a fermentation tank end cover (9), wherein the feeding barrel (1) penetrates through and mounted in the fermentation tank end cover (9); packing (7) is arranged on each of the two sides of the fermentation tank end cover (9); a sleeve (8) is mounted outside each packing (7); the packing (7) tightly presses against a pressing plate (5); a ball ring (4) is mounted between the pressing plate (5) and a corresponding supported flange (3); the supported flange (3) is connected with the fermentation tank end cover (9) through a tensioning bolt group (2); a spacer ring (12) is mounted on one side of the fermentation tank end cover (9); the spacer ring (12) is fixed on the outer wall of the feeding barrel (1) through a set screw (13). The drum-type dry-process methane fermentation tank sealing device effectively solves the problem that many air leakage points exist during the operation of a fermentation tank, and has the advantages that the structure is simple, the market popularization value is great, and the like.