Under special working conditions, vibratory excavation can reduce excavating resistance and improve work efficiency for engineering machinery. The theoretical models of coordinate transformation for excavating devices, vibratory driven mechanisms, and solutions for excavating forces are established. The compound flow control signals produced by normal excavation and vibratory excavation are applied to a bucket cylinder. The excavating force′s characteristics, trace distribution, and work efficiency are analyzed under the conditions of different frequencies, waveform and flow control scales. The key problems of square wave and triangular wave, which cannot be differentiated under normal conditions, are solved using Fourier series in the flow control signal. The vibration model of flow control is verified, analyzed by numerical calculation, and tested. The results show that the vibrating excavation driven by the bucket cylinder is a kind of one-dimensional vibration, and a higher vibration digging force can be acquired using a square-wave vibration control signal or by increasing the vibration frequency and flow control scale. This research can provide a theoretical basis for determining control parameters of vibratory excavation.