Cr-Al-N coatings are the most promising candidate for high-speed cutting tool PVD coating application for the outstanding anti-oxidation ability and hardness stability at high temperature due to their superior thermal stability.Its in great need to improve their hardness,which is lower compared to the classic Ti-Al-N coatings,to boost their comprehensive mechanical properties.Cr-Al-N coatings were deposited on cement carbides and high speed steels using highly-ionized cathodic arc evaporation.Microstructure and morphology were studied by XRD,SEM and TEM.Mechanical properties was studied by nanoindentation,Vickers indentation and scratch test.As-deposited Cr-Al-N coatings show smooth cross-sectional morphology and 7μm thickness on 1-fold rotation samples.Droplet particles are plat in shape and little in quantity,uniformly distributed on the surface.XRD show a more randomly oriented phase arrangement compared to other researches.TEM results show nanoscale wide columnar grains,which are also indicated via large FWHM of XRD peaks.The Cr-Al-N coatings exhibit a superhardness of 41.1GPa.Moreover,Vickers indentations morphologies show only a few circular cracks and no radial cracks exist,indicating great toughness of the coatings.Critical loads Lcl and Lc2 are 32.9N and 71.5N respectively,and CPRs is 1270.6N2.The superior overall mechanical properties of the as-deposited Cr-Al-N coatings attribute to the nano-grain structure with little amounts of droplets,which arise from high ionization deposition process.