Abstract: Milling of thin-walled titanium aluminide workpieces readily induces chatter vibration, severely compromising machined surface quality. To address the stability issue in machining such workpieces with ball-end mills, a dynamic milling force model for the ball-end mill and a dynamic model incorporating three-dimensional (3D) dynamic coupling of the tool-workpiece system were established. Modal parameters were obtained from hammer impact tests, while milling force coefficients were identified via the average milling force method. The stability lobe diagram (SLD) was solved using the full-discretization method based on these parameters. Comparative analysis demonstrated that the critical depth of cut predicted by the 3D model was lower than that of the 2D model due to the inclusion of the workpiece's dynamics in the Z-direction. To validate the prediction accuracy of the 3D model, milling experiments were conducted. The machining stability state was determined by integrating cutting force spectrum analysis with machined surface topography characterization. Results indicate that stable/unstable regions predicted by the 3D SLD closely match experimental findings. In contrast, predictions from the 2D SLD show misjudgments, confirming the superior predictive accuracy of the 3D model. Furthermore, parametric sensitivity analysis elucidates the impact of key modal parameters on the SLD. An increase in natural frequency causes the SLD to shift toward the high-speed region and raises the critical depth. Additionally, increases in both the damping ratio and modal mass bolster the system's chatter resistance.