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A method of compacted soil rotary tilling with variant frequency vibrationis proposed. The tea garden soil physical parameters was measured with soil triaxial test referring to the MAT147 soil model from LS—DYNA material library, then a soil constitutive model of the southern hills’ harden soils and the finite element numerical simulation model for soil vibratory rotary cutting process were built. Through 3-D numerical simulation and analysis, the influence rules on soil cutting resistance caused by many factors of external vibration excitation such as amplitude, frequency and vibration model were studied, and the optimal vibration operation parameters conducive to soil cutting resistance reducing was deduced and confirmed. The results show that the finite element method SPH is effective for large strain and high strain rate numerical simulation of compacted soil rotary cutting, and choosing appropriate vibration frequency, amplitude and vibration types of vibration excitation can reduce tillage mechanism power and improve working efficiency.