Abstract: AC servo system is widely used in industrial control field, but the practical application in the controlling of astronomical telescope is still in the initial stage. In this paper, ground-based wide-angle camera (GWAC) which is the ground observation equipment of SVOM astronomical satellite is used as the research platform, and the AC servo system is applied to the turntable controlling of telescope. The telescope's tracking speed accuracy, tracking accuracy, pointing accuracy and other key technical indicators are tested and compared with the indicators of stepper motor system. The test results show that the two systems have high precision in low-speed controlling. AC servo system has advantages in high-speed controlling, with wider speed range, faster speed regulation and smoother running. In addition, AC servo system also has low noise, high torque, high performance and low price. The interference of AC servo system with the CCD is tested by experiment. The results show that interference of AC servo system with CCD is in acceptable range. In short, the AC servo system can be used for the turntable controlling of small and medium-sized telescope, especially for the system of fast rotation and pointing.