Taking full advantages of the EtherCAT, such as flexible topology,simple configuration, high speed and high efficient data transmission, good real-time and synchronism as well as TMS320F28335’s rich peripheral functions, a slave device with EtherCAT network port was designed, and a distributed servo motion control system was constructed based on EtherCAT. The hardware and software design of the system were given. Three servo system control models were realized, that were position control, speed control, torque control as well as real-time data transmission.