<p>Titanium alloy complex curved surface parts are widely used in aerospace and other fields. In their NC machining process, ball-end cutters are frequently employed, particularly for semi-finishing and finishing operations. However, the ball-end cutter has the problem of low cutting speed at the end. Under traditional constant spindle speed (TCSS) machining, the frequent changes of tool posture will affect the surface quality and tool wear. Based on the speed ratio function model, the velocity effect-sensitive region for the ball-end cutter is determined. By analyzing tool wear characteristics under different tool postures in TCSS machining, a variable spindle speed (VSS) machining method for curved surfaces based on PowerMill post-processing utility (PM-post) is proposed. This method is based on the machining inclination angle as the criterion, and the relative constant cutting speed is taken as the target in the velocity effect-sensitive region. The dynamic matching between the tool posture and the spindle speed is realized, and the machining surface quality is improved. Outside the velocity effect-sensitive region, the constant spindle speed (CSS) machining strategy is adopted to avoid the rapid tool wear under the condition of large inclination machining. Finally, the Ti6Al4V surface milling verification experiment was carried out. The experimental results show that the VSS-CSS machining strategy reduces the average surface roughness <i>Ra</i> of the flat area by 44.37% compared with the TCSS machining, and the cutting force of the tool along the feed direction is significantly reduced. The VSS-CSS machining strategy does not cause rapid tool wear, and the increase is less than 10%. The effectiveness of the VSS-CSS machining method proposed in this paper is verified, which provides an innovative solution for the precise and efficient machining of complex curved parts and has significant engineering application value.</p>