The invention relates to a tree growth suppressor which comprises a clamp, a strong spring, a connector, a fastener holder, a fastener bolt, a fastener crank and a baffle plate. The tree growth suppressor is mounted on a tree trunk, the tree trunk can contact with the baffle plate when growing, so that the fastener crank connected with the baffle plate falls off from the fastener bolt, a fasteneris opened, the strong spring loses limitation and pops open, one bent end of the strong spring moves up, two portions of the clamp are closed and clamped on the tree trunk, sharp sawteeth on the clampof the suppressor cut off or cut tree barks, nutrients cannot be transported to the top end of a tree, and tree growth is suppressed. The tree growth suppressor is simple in structure and easy to mount, tree growth can be effectively suppressed, line tripping faults caused by insufficient safety distance between the tree and a lead can be greatly decreased, manpower and material resources consumed for inspection of the height of the tree below the lead and tree cutting and shearing are saved, and working efficiency is improved.