The digging resistance of soil can be reduced greatly if the bucket is vibrating when the hydraulic excavator is working. The resistance-reducing mechanism of vibratory excavation is researched theoretically. The soil cutting experiment indicates that the interior friction angle and the shear intensity of soil is reduced; and the maximum principal stress is decreased due to the vibration load; it induces the decrease of digging resistance. The comparison simulation experiment research on the failure process of soil under static load and vibratory load has been carried out. The result shows that soil intensity is obviously decreased under vibratory load and destroyed earlier than that of static load. The digging resistance reduced 50 % under vibratory excavation when tracking the load in X-direction.