Abstract: In the 3C electronics industry, titanium alloys are increasingly used in products such as smartphone frames and smartwatches. The machining of 3C titanium alloys demands high cutting speeds and excellent surface quality, placing stringent requirements on tool performance. The structure of end mills significantly influences tool life. This study adopts a combined approach of finite element simulation and cutting experiments to optimize the design of end mill structures, simulating the side milling of smartphone frames. The optimal tool structure was found to have a 5° circumferential rake angle, a 10° circumferential clearance angle, and a straight clearance surface, which resulted in the longest tool life. Observations using a 3D digital microscope revealed that the primary failure modes of the end mills were bonding wear on the rake face and groove wear on the clearance face, with the failure mechanism being titanium alloy built-up edge formation and surface hardening. By integrating simulation and experimentation, this study enhances the design efficiency of key parameters for end mills and provides a theoretical basis for structural optimization.