A feeding device includes a guiding assembly and a clamping mechanism. The guiding assembly includes a guiding rod and a transfer rod coupled to the guiding rod. The transfer rod includes a rack. The clamping mechanism includes a driving assembly and a clamping assembly. The driving assembly includes a support frame, a first driver coupled to the support frame, a gear coupled to the first driver and meshing with the rack, and two guiding members adjustably coupled to the support frame and positioned at opposite sides of the guiding rod. The guiding members is latched to the guiding rod and configured to move the support frame to adjust a backlash between the gear and the rack. The clamping assembly is coupled to the support frame.