Printing plate feeding and discharging device of full-automatic plate changing system of offset press

The utility model discloses a printing plate feeding and discharging device of a full-automatic plate changing system of an offset press. The printing plate feeding and discharging device comprises a plate box, a new plate hooking mechanism and a plate returning mechanism. The plate box is installed on the rear sides of wallboards on the two sides of the offset press in a back-and-forth switching mode from the vertical state to the inclined state. The plate box comprises a rectangular frame which is composed of an upper baffle and two side baffles and provided with an opening in the lower end. The plate box is divided into a new plate bin and an old plate bin through an upper partition plate, a middle partition plate, a lower partition plate and a plurality of inner supporting strips. One side baffle is provided with an old printing plate withdrawing opening corresponding to the old plate bin and is provided with a new printing plate inserting opening corresponding to the new plate bin; the new plate hook mec