The utility model provides a chain dismounting device. The device comprises a base, a chain locking device and a push-out device used for pushing out a pin buckle of a chain. Wherein a supporting seatis arranged on the base, the chain locking device comprises a screw rod and a pair of locking pieces which are arranged on the screw rod and used for locking a pin buckle on a chain, the pair of locking pieces move reversely when the screw rod rotates, and the screw rod is rotatably arranged in the supporting seat; wherein the push-out device comprises a push piece, a push rod arranged on the push piece, a screw rod and a tightening cap screwed on the screw rod, the push piece is arranged on the screw rod in a sliding mode, the screw rod is connected with the screw rod, and the tightening capis arranged on the outer side of the push piece. The chain dismounting device solves the problems that in the prior art, chain dismounting wastes time and labor, the working efficiency is low, and chain deformation is prone to being caused.