Objective To study the effect of silicon addition on mechanical properties of the VAlN hard coatings. Methods Using the two-target ( V50Al50 target and Si target) magnetron co-sputtering machine to deposit the VAlSiN hard coatings. The silicon content was adjusted by the power applied to the silicon target. Results The silicon added in the coatings was all in the Si₃N₄ phase, which had a grain refining effect. When the silicon content was low, the mechanical properties ( both hardness and wear rate) of the coatings were improved. However, once the silicon content was higher than that, Si₃N₄ became the main phase of the coatings, and the mechanical properties of the coatings turned worse. Conclusion Adding a little silicon to the VAlN hard coatings could improve their mechanical properties.