Currently,the EtherCAT bus is commonly used in industrial motion control for communication between master and slave stations,and a large amount of motion data information is transmitted on the EtherCAT bus.Based on this,a servo system error and interpolation algorithm error identification method for EtherCAT bus was proposed.The data on the EtherCAT bus during the motion process were captured through ET2000 and WireShark,valid data were filtered to generate .pcapng file,this file and the ENI.xml file of the motion control system were analyzed to obtain target position and actual position information,and finally error analysis were conducted on the obtained position information.Corresponding motion trajectories were designed for various types errors.Multiple sets of motion control experiments were conducted on the machine tool for single axis point motion,two axis interpolation motion,and two axis prospective interpolation motion.Errors such as servo response lag,servo dynamic performance mismatch,tracking error,positional jitter,and interpolation algorithm error were identified,obtaining the motion control accuracy of single axis and the ability of multi axis motion to cooperate with each other.