The invention discloses a loading and unloading device for packing machines. The loading and unloading device comprises sliding plates, a loading plate and an unloading plate; a second connecting rodis mounted in a first connecting rod in a sliding manner; a fixing bracket is rotatably mounted on the first connecting rod; grooves are formed in the second connecting rod; a first supporting columnand a second supporting column are mounted on one side of the lower end of each of the loading plate and the unloading plate; second pulleys are rotatably mounted on the unloading plate; protective fences are mounted on the two sides of the upper end of each of the loading plate and the unloading plate through fixing rods; the two sliding plates are mounted at the end walls of one sides of the unloading plate and the loading plate; first pulleys are mounted on the sliding plates in a sliding manner; guide rods are mounted on one side, departing from the corresponding sliding plate, of the loading plate in a sliding manner through mounting plates; a conveying belt is mounted on the loading plate through driving wheels and driven wheels; a rotating shaft is rotatably mounted at the side endface of the loading plate; and a motor is mounted on one side of the rotating shaft. The loading and unloading device has the advantage that the loading and unloading device is suitable for use in thesmall packing machines in different lengths and heights.