Abstract: In high speed machining with multi-axis linkage, the dynamic error of machine tool caused by motion parameters is an important factor to produce machining errors. In this paper, the dynamic error and static error models of EtherCAT bus CNC machine tools are established by using the rod instrument QC20-W and the industrial Ethernet probe tool ET2000 as measuring tools. Firstly, based on the homogeneous coordinate transformation theory, the mathematical relationship among the rod length variation and the dynamic and static errors of the machine tool is established. Then, according to the different characteristics of the two kinds of errors, we construct the static error polynomial expressed by coordinate positions and the dynamic error low order sine polynomial expressed by velocity, acceleration angular frequency, and phase. In order to obtain the angular frequency and phase information of velocity and acceleration in sinusoidal polynomial, Wireshark and ET2000 are used to capture the position information of axis, and the velocity and acceleration are obtained by differentiating. Wavelet transform is used to reduce the noise in position information. Finally, the least square theory is used to solve the unknown coefficients in the error expression. The results show that instruction speed is the main factor of dynamic error, and acceleration is the secondary factor. When the acceleration is constant and the instruction speed increases from 20 mm/s to 40 mm/s and 80 mm/s, the proportion of dynamic error in the total error increases from 2.13% to 11.74% and 49.15%. When the command speed is unchanged and the acceleration increases from 200 mm/s² to 800 mm/s², the proportion of dynamic error increases from 22.72% to 26.83%, respectively.