TiAlN/TiN multilayer PVD coated carbide is one of the dominant tool materials for the milling applications of Inconel 718 due to its high hardness, high wear resistance, and high thermal stability. In this paper a study was undertaken to investigate the wear of TiAlN/TiN multilayer PVD-coated carbide tools during milling of nickel-based superalloy Inconel 718 at high speeds. The wear patterns and wear mechanisms were analyzed. Results show that the dominant wear patterns were coating delamination, thermal crack, micro-chipping，chatter marks and breakage. When the cutting depth was 1mm, the coated tool was predominantly subjected to adhesion and diffusion wear throughout the duration of cutting. Adhesive wear on one hand accelerated the extension of thermal crack, on the other hand promoted the diffusion wear. When the cutting depth was 3mm, the tool life was determined by chatter which could lead to failure of the cutting tool in very short time.