In this paper, Chromium nitride (CrN x ) thin films were deposited with reactive magnetron sputtering method. EDX, X-ray diffraction and transmission electronic microscopy were employed to characterize their chemical compositions, phases and microstructures. Microhardness and elastic modulus were evaluated using a microhardness tester and the effect of N 2 partial pressure on the composition, phases, microstructure and mechanical properties of CrN x thin films was investigated. The results show that the phase formation of CrN x thin films varies from Cr+Cr 2 N to single-phase Cr 2 N, and then Cr 2 N+CrN to nearly single-phase CrN with increasing N 2 partial pressure. The microhardness values of these films make a distribution ranging from HV 21.4 to 27.1 GPa, and when the atom ratio of Cr:N is 1:2 and 1:1, thin film reaches peak hardness values (HV 27.1 and HV 26.8 GPa, respectively), while the elastic modulus is maximal (350 GPa) when single-phase Cr 2 N films is formed.