Abstract：High-performance servo control system has been developed from analog control to digital control, with performance being improved and with a broad application in military and civilian areas. The servo control system based on fieldbus with high reliability, speed and stability becomes the development trend of servo motor control systems. This paper discusses the difficulty of organizing the net structure and the rigorous real-time requirement in the scene of high-performance servo control system, and proposes to use the Ethernet for control automation technology. On the data link layer, EtherCAT adopts a real-time soft core，and uses independent channels for the process data transmission，which improves the real-time quality of the system. The EtherCAT's architecture, the working principle and the communication protocol are reviewed in this paper, high-performance AC serve control systems are designed based on EtherCAT, together with a slave device by using EtherCAT slave controller ET1100 and DSP TMS320F2812, which can achieve an accurate position control by using the EtherCat structure of one-master and more-slaves. The hardware and software design of the servo system is given, which realizes the real-time data transmission and position control.