Cutting signals can monitor the cutting status in metal cutting process such as acceleration, cutting force, motor current, and acoustic emission. In this paper, cutting force and spindle acceleration signals were analyzed and compared in milling titanium alloy thin-wall components and non-thin-wall components under the same cutting parameters. Tool wear was analyzed during the whole cutting process. Frequency spectrum and wavelet analysis methods were used in this study to illustrate the impact of tool wear on cutting force in milling two types of workpiece such as thin-wall and non-thin-wall components. The experimental results showed that cutting vibration in milling thin-wall components is obviously higher than in milling non-thin-wall components owing to its weak rigidity, which caused relatively small cutting force for the smaller cutting load. The cutting force frequency was decreased from the tooth passing frequency (TPF) to spindle frequency (SF) because each cutting edge withstands different cutting loads caused by the tool wear of each cutting edge. The energy contribution of TPF is biggest in early milling process, and the energy contribution of SF is well over that of FPF in the late milling process (when VB is greater than or equal to 0.18 mm) because serious tool wear caused each cutting edge to bear the different cutting loads.