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The cultivation and land preparation work in mulberry plantations is the important foundation for improving mulberry leaf yield. Based on the mulberry planting mode and the requirements of cultivation and land preparation work, a vertical rotating rotary harrow suitable for mulberry plantations was designed and optimized. According to the mulberry plantation planting and cultivation requirements to determine the rotary harrow machine structure, through the theoretical analysis of the harrow knife operation process and kinematic analysis, the harrow knife structure parameters were determined. Using the discrete element method to simulate the rotary harrow operation process, and the influence of different camber angles on the torque of the harrow knife and working quality of the machine and the variation law of the torque during the harrow operation were analyzed. Taking rotor speed, forward speed and plowing depth as test factors, and taking soil breakage rate, surface flatness after harrowing and soil weight as test indexes, a three-factor, three-level orthogonal rotary combination field test was carried out to analyze the influence of each factor on the operational effect of rotary harrow. The test results showed that the rotor speed and forward speed on the soil breakage rate, harrowing surface flatness and soil weight was very significant;the effect of plowing depth was only significant on the soil breakage rate, and there was no significant effect on the harrowing surface flatness and soil weight. The optimal combination of operating parameters was calculated as follows: rotor speed was 350 r/min, forward speed was 0.7 m/s, plowing depth was 20 cm, soil fragmentation rate was 97.89%, surface flatness was 11.04 mm after harrowing, and soil capacity was 1.11 g/cm3. The verification test was carried out with the optimized operation parameter combination, and the soil breakage rate was 97.29%, surface flatness after harrowing was 11.53 mm, soil capacity was 1.07 g/cm3, which was consistent with the optimized results, and it met the operational requirements.