Optimization of the process parameters of arc ion plating so as to improve the structure and properties of TiAlN coatings has important practical value in the application of TiAlN coatings. In the work, TiAlN coatings were deposited by pulsed bias arc ion plating, and the influence of duty ratio of pulsed bias on the structure and properites of TiAlN coatings was studied. It was found that the density of surface defects and surface roughness of TiAlN coatings are first decreased and then increased with the increase of the duty ratio; and the density of surface defects and surface roughness is the lowest when the duty ratio is 70%. The micro-hardness and wear resistance of TiAlN coated samples is first improved with the increase of the duty ratio, while the further increase of the duty ratio above 50% has an adverse effect on the micro-hardness and wear resistance. The key wear mechanism of TiAlN coatings includes adhesive wear and oxidation wear when Si₃N₄ ball is used as the friction pair.