TiAlN thin films were fabricated via arc ion plating on the W18Cr4V high-speed steel under different negative biases. The influence of negative bias on the microstructure, phase, and crystalline orientation, hardness, and deposition rate of the films were investigated. The results show that the films have a coarse surface at too high or too low biases, resulting in lower hardness. The largest deposition rate is achieved at -200 V bias. The TiAlN thin film has a (111) preferred orientation when deposited at -150 V bias, where the largest hardness is achieved.