Mo-C-N-Si coating on Mo substrates was prepared. The oxidation property of the coating at 1600 oC in air was investigated. Microstructures and phase composition of the coatings were analyzed by means of SEM and XRD, respectively. Results show that Mo-C-N-Si coating consists of the MoSi2, SiC and Si3N4 phases. The middle layer of Mo2C+MoxN can be observed in the coating. Mo-C-N-Si coating becomes four layer structures, i.e. SiO2 oxidation layer, MoSi2 body layer, Mo5Si3 layer and Mo2C+MoxN layer at the initial stage of oxidation duet to the diffusion and oxidation. However, Mo-C-N-Si coating fails in the later stage, probably because it changes to double-layer structures of Mo2C+MoxN layer and Mo3Si+ Mo5Si3 layer. In addition, the thermal shock resistance of the coating is improved by the addition of the C and N elements.