Abstract: It is researched the effect of digital phase shifter quantization errors on the phase center of phased array antenna in the paper. Firstly, the method of calculating phase center of phased array antenna is presented. The phase center of phased array antenna can be calculated accurately according to the phase distribution at far field. Secondly, the simulation based on the proposed method is carried out on a example array with 5 digital phase shifter, and the variation of the phase center on different scan angles is acquired. The calculating results indicate the digital phase shifter quantization errors of the phased array antenna can make an obvious effect on its phase center, moreover, the effect is closely related to the phase shifter digit and scan angle. The conclusion can be used in designing of high-precision phased array antenna.