Abstract: In order to solve the problems of the tough working environment, high labor intensity, low work efficiency and expensive operating cost of dwarf-dense jujubes plantation in Xinjiang. A three-dimensional copying and trimming device was designed in this paper to realize the three-dimensional layered copy cylindrical pruning of individual jujube trees. The kinematics models and mechanics models of the cutters in the process of jujube cutting were established by theoretical analysis of pruning knives cutting jujube branches. The results showed that the theoretical critical speed was 1020 r/min without missing cutting when the circular saw blade cutter was used. When the diameter range of the cutter was 100-400 mm and the diameter range of the pruning was 5-17 mm, the theoretical sawing power P was 56-1309 W. Four simulation models based on multi-body dynamics were established with cutter rotating speed of 2000 r/min and pruning device moving speed of 0.4, 0.7, 1.0 and 1.3 m/s to conduct motion analysis. The simulation results showed that when the moving speed of the pruning device was 1.0 m/s, the contour of trajectory was approximate to a circle, and the determination coefficient R~2 of arc curve fitting was 0.98. The fitting degree was high, which met the requirements of cylindrical trimming of the pruning device. It provides theoretical basis and technical support for the design of jujube pruner.