The utility model relates to a tall ornamental trees and shrubs cropper, which mainly comprises a base ascending platform, side-trees-holding preventing mechanism, a work platform rotary mechanism, a mechanical arm lifting mechanism, a mechanism arm telescopic mechanism, a branch collecting trimming mechanism and a motor. The base ascending platform is of a cutting-V-shaped ascending platform; the side-trees-holding preventing mechanism consists of a crankshaft sliding block mechanism and a four-link-lever mechanism; the work platform rotary mechanism realizes the rotation of the platform by adopting four worm and gear reducer to drive four trundles to roll on the work platform; the mechanical arm lifting mechanism adopts a crankshaft swinging rod mechanism; the mechanical arm telescopic mechanism adopts the transmission of a screw lead nut and a friction wheel; and the branch collecting trimming mechanism is interlocked with a mechanical hand through the straight-line movement of an electric saw. With the tall ornamental trees and shrubs cropper, the work conditions of the garden workers can be improved, and the labor intensity can be reduced, and the safety problem of the worker caused by climbing up the trees for trimming can be eliminated. The cropper has small volume, convenient application, low cost and easy popularization.