At present, the mechanized harvesting method of Cyperus edulis is mainly forward rotary tillage excavation, but there are problems in the work process such as large working resistance, low soil fragmentation rate and high fruit burying rate. The discrete element model of the rotary tiller and the cedar agglomerates was analyzed and established, the discrete element simulation test of the excavation process was carried out combined with EDEM, and the structural parameters and value ranges that affected the rotary tiller's working resistance and the torque of the tool shaft were determined. Design-Expert experiment optimization and regression analysis were carried out to determine the best structural parameters of the rotary tiller, which were as follows: bending angle of 130°, working width of 45mm, compared with the normal rotary tillage method under the same parameter settings, the working resistance was reduced by 8.6%, the torque of the cutter shaft was reduced by 5.9%, which proved that the anti-rotating excavation had the effect of reducing resistance. In order to test the performance of the optimized rotary tiller, the fruit burying rate and the soil breaking rate were used as the test indicators to conduct a comparative test. The results showed that the reverse rotary operation method had a fruit burying rate of 1.07% and a soil broken rate of 93.48%, which were compared with the standard rotary cultivator. Compared with the new type rotary scalper, the burial rate of tubers of Cyperus edulis was reduced by 1.2 percentage points, and the soil broken rate was increased by 1.3 percentage points, which improved the harvesting efficiency of Cyperus edulis.