Acting force of soil is a complicated variable under vibrating working condition. In order to study the effect of penetration angle, amplitude and vibration frequency on acting force of soil and traction resistance, the soil was taken as viscoelastic material. The mechanics model for vibratory subsoiler and soil system was established considering piecewise acting force of soil. It adopted asymptotic method and numerical integral to solve and analyze this model, and the results showed that when the penetration angle was 45°, the amplitude was 0.001 m and the vibration frequency was 10 Hz, acting force of soil was relatively small. A vibratory subsoiler was tested in site to verify the correctness of the model through comparison of the simulation data and experimental data. The analysis further shows that the vibration can be used to reduce acting force of soil and traction resistance of tractor and improve quality of soil subsoiling.