In this work, the Chromium Aluminum Nitride (CrAlN) coatings were prepared on TC11 titanium alloy by arc ion plating. The effects of negative bias voltage on the micro-structure and mechanical properties, such as hardness and elastic modulus of the coatings were investigated by X-ray Diffraction (XRD), scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDX) and nano-indentation. A series of solid particle erosion experiments were also conducted to study the influence of bias voltages on the solid particle erosion resistance of CrAlN coatings. It has been found out that the preferred growth orientation of CrA1N coatings gradually varied from (200) to (111) crystal plane with the bias voltage changing from 0V to 200V. The hardness increased from 15.1 GPa to nearly 20 GPa. At the same time, the number of macro-particles and pinholes decreased with the surface gradually flattens, which improved the erosion resistance of the CrAlN coating. The CrAlN coating deposited at the bias voltage of 150V obtained minimum erosion rates which were 0.032 μm/g at 30° and 1.869μm/g at 90°, respectively. These results indicate that the CrAlN coating formed at an appropriate bias voltage can achieve an excellent solid particle erosion resistance.