Approximately 2 μm thick CrN and CrAlN coatings were synthesized on silicon and spring steel substrate by multi-arc ion plating technology. The nanoindentation techniques, Auger electron spectroscopy (AES) analysis, scanning electron microscopy, X-ray diffraction and oxidation furnace were used to investigate the mechanical property, oxidation resistance and microstructure of the coatings. The XRD data showed that the CrN and CrAlN coatings exhibited B1 NaCl structure. Nanoindentation measurements showed that as-deposited CrN and CrAlN coatings exhibited a hardness of 19 and 30 GPa respectively. Compared with CrN coatings, the CrAlN composite coatings show much better oxidation resistance. And the oxidation resistance ability will enhance with increasing Al content, because A12O3 will form after oxidation in high temperature condition which could reduce the diffusivity ability of oxygen.