Abstract: To analyze the interaction between the digging shovel and the soils,as well as the stress variation of the cassava roots and the influence of structural parameters of the digging shovel to the digging performance,a visual dynamic simulation model of the digging shovel-stem-root-soil system is established,which is based on the ANSYS/LS-DYNA explicit dynamic software,the Lagrangian algorithm,the Smoothed particle hydrodynamics (SPH) algorithm and the modified Mohr-Coulomb yield criterion.The digging process is numerically simulated with the proposed model and the loosening soil mechanism of the digging shovel,soils deformation,fragmentation and loosening,and stress variation of cassava roots are studied at micro level.In addition,the effects of shovel structural parameters on the traction resistance,the loosening soil,and the effective stress of cassava roots are investigated by using a factorial experiment with single factor.The results show that soils are bended and thus broken into fragments when they are uplifted by the digging shovel,which is the main reason for soil loosening.The extrusion caused by soils bending and deformation leads to the bending deformation of cassava roots during loosening soils.When the penetration angle and the width of digging shovel increase,the traction resistance will increase and the soils loosening is improved.But the bending deformation and the effective stress of cassava roots also increase,which may break the roots and thus result in loss in cassava yield.When the wingspan angle of digging shovel is enlarged,the traction resistance and the soil loosening will decrease.