Abstract: Sugarcane-cutter system dynamics simulation model was established and suitable material parameter model of sugarcane was obtained by using explicit dynamic simulation software ANSYS/LS-DYNA and inverse method. The precision of the simulation model was verified by physical experiment. Based on the establishment of soil-sugarcane-cutter system dynamics simulation model, dynamics simulation experiments were carried out and correlative mathematic models were built. The effects of soil soft-hard state on sugarcane maximum cutting force and broken biennial root was investigated.The results showed that the soil soft-hard state had more effective on sugarcane axial shear stress than that on sugarcane maximum cutting force.The maximum cutting force of two-blade cutting sugarcane is smaller than that of one-blade. The maximum force for cutting under the ground was larger than that for cutting over the ground,but the average axial shear stress for one-blade cutting under the ground was 43.3% less than that for cutting over the ground. Moreover, the average axial shear stress for two-blade cutting under the ground was 49% less than that for cutting over the ground. Cutting sugarcane under the ground could effectively reduce the rate of broken biennial root.