The utility model relates to agricultural machinery equipment technical field discloses a disc rubbing crusher's dead knife adjusting device, and it includes the dead knife, and the both ends of dead knife are equipped with the dead knife mounting panel that clamps in the guide rail with two, and dead knife mounting panel inboard is equipped with the pneumatic cylinder connector, and two pneumatic cylinder connectors are connected with the piston end of two pneumatic cylinders respectively, and the closed -loop type hydraulic control return circuit is formed with the hydraulic pump to two pneumatic cylinders, is equipped with rotatory screw rod and piston in the inner chamber of the pump body of hydraulic pump, the utility model discloses a rotating the rotatory screw rod of hydraulic pump and controlling the flexible of pneumatic cylinder piston, and then realize hammer leaf relative position's on disc rubbing crusher's dead knife and the arbor regulation, labour saving and time saving has improved production efficiency, the motive force of hydraulic control return circuit pairing rotation screw rod has amplification effect, and the operation personnel only need less drive power, can realize the removal of dead knife. The utility model discloses simple structure, the simple operation to the cost of manufacture is lower.