This paper aims to investigate the evolution of microstructure, nano-hardness and thermal stability of the CrWN coating with different W content under the N2 annealing atmosphere. The CrWN coatings with different W contents were synthesized by the plasma enhanced magnetron sputtering technique. The microstructure, surface quality, dimensional accuracy, nano-mechanical property and thermal stability of the as-deposited and annealed CrWN coatings were investigated by the scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), nanoindentation and atomic force microscopy (AFM). The CrWN coating was composed of the face-centered cubic CrN+W2N phases, the CrN and W2N sublayers were deposited alternately, and showed a typical coherent growth. With the increase of W content, the nano-hardness of this coating increased from 12.9 GPa to 15.5 GPa, and its roughness decreased and tended to be stable. After the annealing treatment in nitrogen atmosphere, the reaction with the trace impurity gases in the atmosphere intensifies, the hardness of the CrWN coating decreased significantly with the increase of W content, from 13.5 GPa down to 5.2 GPa. Meanwhile, the WO3 phase in the oxide layer increased obviously with the increase of W content, which consequently resulted in the significant increase in surface roughness and thickness of the coating. The CrWN coating exhibited excellent surface quality and nano mechanical property, but suffered from the severe surface coarsening, volume expansion and mechanical degradation after the N2 environment annealing because of the oxidation erosion. The microstructure damage and performance degradation of the annealed coating were aggravated with the increase of the W content. The current results confirmed that the oxidation damage was a key factor to be considered in the glass precision molding application of the CrWN coating. Therefore, when CrWN coating is used as a coating for optical glass precision molding molds, it should work in a high vacuum or high purity inert gas environment.