In the high-precision GPS positioning applications,the antenna phase center calibration significantly impacts the survey accuracy. This article introduces the experiment study of precise calibration of GPS antenna phase center variations based on automatic survey robot GPS which is funded by Crust Movement Observation Network of China project. In this paper,the main derivations of the principle and implementation procedure are described step by step. Comparing with the known calibration parameters,the horizontal accuracy is estimated about 2mm and the vertical accuracy is estimated about 3mm. This study is of practical significance to improve the accuracy of GPS positioning and to popularize the application of calibration of antenna phase center variation based on survey robot.