Abstract: In order to study the effect of cutting force and speed on the dynamic positioning error of XY table of CNC machine tool, the dynamic error characteristics of XY table under the influence of cutting force were analyzed comprehensively. The accurate calculation model of dynamic positioning error components caused by error sources such as ball screw assembly, guide rail system, table surface and friction force is established, and the theoretical model of XY table dynamic positioning error is derived. According to the theoretical model, cutting force, speed and friction are the main sources of dynamic positioning error of XY table. The theoretical model of dynamic positioning error under cutting force is analyzed, calculated and simulated, and the validity of the theoretical model is verified. It is proved that the cutting force has an effect on the dynamic positioning error of the table, and the dynamic positioning error is minimum when the table moving speed is 4 mm/s under different cutting force, and the speed is defined as the best moving speed. The results of this study lay a good foundation for setting up the positioning error prediction and compensation model of NC machine tool to improve the machining accuracy.