A knapsack electric trimmer was designed to perform dynamic and kinematic analysis of the sawing process and to build a functional model based on power and torque. Taking the trimming power,torque and cutting quality as indicators,the main influencing factors were selected by theoretical analysis,and the mixed orthogonal test was carried out. The optimal combination parameters were predicted by range analysis and variance analysis. The results showed that the optimal number of cutter teeth,the diameter,and the speed was 40,180 mm,and 2 000 r/min,respectively. The test results of verification test of citrus branches with a diameter of 30 mm using an optimized pruning machine showed that the average incision quality and the torque was reduced by 2.8% and 0.3%,the power was increased by 2.6%,and the variation was small. The rationality and effectiveness of the bench test was verified. This combination of parameters can effectively reduce the trimming power and meet the trimming requirements.