Abstract: The effect of the amplitude and phase error on the phase center of array antenna is investigated in the paper. Firstly, the method of calculating phase center of array antenna is briefly presented. The phase center of array antenna can be calculated accurately according to the phase distribution in the far field. Secondly, the simulation based on the proposed method is carried out on an example array with amplitude and phase error of uniform and Gaussian distribution, and the variation of the phase center on different error distribution is acquired. The calculating results indicate that the amplitude and phase error of the array antenna can make an obvious effect on its phase center, moreover, the effect is closely related to the type of the error distribution and the error limit. The conclusion can be used in designing high-precision array antenna.