Abstract: In the process of five-axis end milling of curved surfaces, the space tool compensation function is usually used to simplify NC programming. However, the tool axis vector is prone to singular solutions during the compensation process, which makes the motion axis of the machine tool move suddenly near the singular position. Projection method is used to detect the singular points in the five-axis end milling process of the curved surface, the tool axis vector is projected on the two-dimensional plane, and the singular points are judged according to the projection length and included angle, which reduces the amount of calculation and improves the accuracy of detection It can quickly and accurately detect the singularity in the process of spatial tool compensation. By restricting the feed rate of the NC program segment in the singular area, the stable speed through the singular point can be realized, which can effectively avoid the sudden change of the machine tool motion axis, improve the surface processing accuracy, and ensure the safe operation of the machine tool.