The invention discloses a shifting fork mechanism for a feeding and discharging device of an automatic assembling machine for paper clips. The shifting fork mechanism comprises a left support, a right support, a cylinder connecting shaft and a shifting fork. The cylinder connecting shaft is mounted in a groove formed by the left support and the right support which are in butt jointing. The shifting fork comprises a key slot, a first shifting piece and a second shifting piece, wherein the first shifting piece and the second shifting piece are arranged on the key slot and form certain included angles with the center line of the key slot. The shifting fork is fixed on the cylinder connecting shaft through the key slot and a protruded key positioning sleeve on the cylinder connecting shaft, the cylinder connecting shaft is connected with an oscillating cylinder, and the shifting fork controls the cylinder connecting shaft to rotate back and forth within a certain oscillation stroke angle under actions of the oscillating cylinder. By the aid of the shifting fork mechanism, discharging operation of assembled paper clips and feeding operation of to-be-assembled paper clips are realized synchronously, time for feeding and discharging is saved, assembling efficiency of the paper clips is improved, and meanwhile, a great quantity of manpower cost is reduced.