Ti-Al-Si-N quaternary coating has recently been developed for industrial applications due to its excellent machining performance. Here, we present a comparative research on Ti-Al-N single layer, Ti-Al-Si-N single layer, TiAlN-TiAlSiN bilayer and TiAlN/TiAlSiN multilayer coatings deposited onto cemented carbide substrates by cathodic arc evaporation. The incorporation of Si into the Ti-Al-N coating results in an increase in hardness and thermal stability due to the formation of nanocomposite nc-TiAlN/a-Si 3 N 4 , and thereby causes an improved performance during continuous cutting. However, the lower toughness and adhesive strength with a substrate reduce its cutting-life during milling. Further optimization of Ti-Al-Si-N coated inserts during milling can be obtained by a structure adjustment from the nanocomposite into TiAlN-TiAlSiN bilayer and TiAlN/TiAlSiN multilayer coatings, which causes an increase to 156% and 172% for the life-time of Ti-Al-Si-N coated inserts, respectively. Our results indicate that the machining performance of coatings containing Si in both continuous cutting and milling can be optimized by the structure design of the TiAlN/ TiAlSiN multilayer, where the coating sustains a high hardness of the Ti-Al-Si-N coating combined with a good cohesive strength with the substrate similar to the Ti-Al-N coating.