Abstract: In order to avoid the impact of velocity fluctuation in five-axis CNC system when the rotation axis linearly follows XYZ axes, a flexible velocity planning method of rotation axis was proposed, which had less calculation and was easy to realize in embedded system. Based on the principle of time synchronization, the velocity planning of the rotation axis was realized by using the motion time constraint of the XYZ axes. The reasonable starting speed, acceleration, driving speed and final speed were calculated, and the T-type speed planning interpolation output was carried out to the servo motor to realize the motion control of the five-axis CNC machine tool. The experimental results verified the effectiveness of the proposed scheme. Compared with the linear following machining of the rotation axis, the proposed control method could also maintain the velocity continuity of the rotation axis when performing multi-segment continuous trajectory interpolation, and each joint ran in a reasonable kinematic threshold range.