Abstract: The low-cost design idea and digital new method of active phased array antennas are researched in this paper. The system structure and cost composing are detailed analyzed at first. And then, starting from collectivity design, the method of low-cost digital array phased array technique is discussed. Finally the reconfigurable scheme of wide-band and wide-angle is proposed to reduce the cost of phased array antennas. The proposed low-cost design method of active phased array antennas have good engineering applied value and science significance, and overcome pure theory research.