The work aims to investigate erosion wear properties and material removal mechanisms of AlCrN coatings on ti-tanium alloy substrates under the solid particle erosion conditions. AlCrN hard coating was deposited onto titanium alloy substrates by cathodic arc ion plating physical vapor deposition (PVD). Scanning electron microscopy (SEM) was used to analyze the surface topography of samples before and after erosion test; energy dispersive spectrometer (EDS) and X-ray diffraction (XRD) were applied to analyze chemical components and phase composition; white light interference profiler was adopted to detect the surface roughness of the sample and the depth of erosion pits after the erosion test; and nano indentation and multi-functional tester for material surface properties was used to analyze harness, elastic modulus and bonding strength of simples. The performance of erosion resistance of samples were evaluated on the erosion tester under high impingement angle. The polished titanium alloy had a smooth surface with no obvious defects. The hardness and elastic modulus were 4.29 GPa and 141.02 GPa, respectively. Growth detects like particles and voids with different sizes were found on the surface of AlCrN coating with the thickness of about 10.5 μm. The hardness and elastic modulus of AlCrN coating were 23.27 GPa and 264.95 GPa, respectively. XRD pattern showed that AlCrN coating consisted of AlN phase and CrN phase. The erosion scar depth of the AlCrN coating was only 1/10 of the substrate at impingement angle of 90°, with a particle velocity of 85 m/s and a particle feed rate of 2±0.5 g/min. By observing and analyzing eroded surface morphologies, impacting pits, extruded lips and micro-cutting trace were found on the surface of titanium alloy substrate, and while micro-cutting trace, plastic deformation of large particle and spalling pits appeared on the surface of AlCrN coating. The erosion behavior of bare titanium alloys is typical plastic erosion mechanism. The erosion behavior of AlCrN coating is plastic erosion mechanism in the early stage of erosion, while both plastic erosion and brittle erosion mechanisms appear with progress of erosion.