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Abstract. In order to improve the applicability of pneumatic implements for pruning jujube tree, the paper put forward an improvement scheme based on the principle of the pneumatic linkage mechanisim. Double-acting cylinder drives connecting link, then the connecting link drive a movable cutter blade rotation relative to a fixed cutter blade, so the branch between the two cutter blades is trimmed. The pneumatic circuit is composed of air-compressor, pneumatic three parts, two-position five-way manual valve and double acting cylinder. For shearing force value of the branches, jun jujube branches of approximate 20 mm diameter was simulated a pruning test by using a movable blade of circular edge based on an universal material testing machine. The result show that t the largest value of peak shear force is 5 kN when the shear angle is 90°, the smallest value of peak shear force is 2.78 kN when the shear angle is 45°. Based on the principle of slider rocker mechanism, the theoretical calculation formula of shear force was obtained by a simplified mechanical analysis of the cutting mechanism. The formula shows that the shear force value of of the pruning mechanisim depends on the four structural parameters such as cylinder action area, rocker length, angle between slider and connecting rod, and pressure angle of four bar mechanism.