Abstract: The high entropy (AlCrTiZrNb) N alloy coatings were synthesized by RF magnetron sputtering.The effect of the ratio of nitrogen to argon flow rates on the microstructures and mechanical properties of the coatings were investigated with X-ray diffraction, energy dispersive spectroscopy and conventional mechanical probes.The results show that the N2:Ar flow-rate ratio had as major impact.For example, as the N₂:Ar flow-rate ratio increased, the deposition rate decreased; the amorphous to fcc solid solution phase-transition occurred, accompanied by emergence of < 200 > preferential growth orientation with Me-N (metal-nitride) structure; the hardness changed in a rapid increase and slow decrease manner.Grown at a ratio of 1:1, the strongest hardness of the FCC solid solution phased (AlCrTiZrNb) N coating was up to 28.324 GPa, mainly because of the formation of saturated metal-nitride phase and because of solid solution strengthening of constituent elements.