Abstract: In order to simplify the driving control module for the high intensity focused ultrasound phased array with hundreds of elements,a phase-control method with high excitation efficiency is proposed.With the help of this method, focused acoustic fields of a 256-element annular spherical-section phased array are calculated and compared with the corresponding fields obtained by using the traditional control method of imposing both amplitude and phase signals. It is shown through simulation and experiments that the therapeutic focusing fields with spatial single-focus can be synthesized validly,under the conditions of simplified driving control module and increased array excitation efficiency. The focal energy aberration,which is brought with this simplification method,can be compensated validly by adjusting the overall input acoustic power.