Due to the dispersion effect and aperture fill effect, essentially, the traditional active phased array antenna is a narrow-band system. To solve this problem, true time delay (TTD) method is massively employed in active phased array antenna design. In this paper, a multi-stage TTD method is proposed to improve the instantaneous bandwidth of antenna array. Firstly, the theory of multi-stage TTD is briefly introduced. Then the antenna radiation pattern performance employing sub-array TTD and multi-stage TTD method are analyzed and compared based on simulation results. Finally, the typical broadband performance of the antenna is tested. When the measured wave position’s frequency is 1.5GHz deviating from the center frequency and azimuth/elevation sweep angle is 60°, the pointing error is reduced from 1.24°/1.63° to 0.47°/0.24° after employing multi-stage TTD method, and the results prove that the multi-stage TTD method significantly expand the instantaneous bandwidth with good engineering realizability.