The invention relates to a safe and convenient automatic fast dismounting device used for bundling, hoisting and unloading cargos and particularly suitable for dismounting a cane bundling and hoisting chain. The invention is characterized in that a lock pin pushed by the elastic force is arranged in a linkage frame; the front end of the lock pin connects with a hanger hinged on a bearing pin; a rotating hook is fixed on the lock pin and borne on a hoisting track fixed in the linkage frame; the contact surface of the hoisting track and the rotating hook is concave-convex surface. The chain canbe dismounted by hooking a dismounting cable hook onto the rotating hook, the rotating hook is pulled to rotate to the convex surface of the hoisting track and drive the lock pin to rise and release the hanger; after rotation, the part where the rotating hook hooks the cable is positioned at the position releasing the cable, so the cable can automatically slide off the rotating hook. The invention has the advantages that the dismounting operation can be carried out safely and conveniently by an operator in the distance; the dismounting can be completed swiftly just by pulling action; a transmitting belt with cargos moving on can be dismounted automatically and quickly.