Titanium alloys are widely used in the aerospace industry for applications requiring high strength at elevated temperature and high mechanical resistance. However, titanium alloys are classified as extremely difficult-to-cut materials owing to their physical, chemical, and mechanical properties, which result in the low material removal rate and the short tool life. This paper presents an experimental research of the tool wear patterns and relevant wear mechanisms during high-speed milling of Ti-6Al-4V with cemented carbide inserts. SEM-EDX analysis showed that nose wear and edge wear were the main tool failure modes during high-speed milling process, which were different from the wear patterns under traditional cutting conditions. Adhesion, attrition and diffusion wear mechanisms, as well as the cracks were responsible for the tool wear.