A Mo-Si-C-N multi-layer anti-oxidation coating was in situ fabricated on C/C composites by fused slurry and reaction-sintering method in nitrogen atmosphere using Mo and Si element powders, and characterized by X-ray diffractometry, optical microscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy with energy dispersive spectroscopy. It is shown that the coating contains three distinctive layers, namely, SiC inner-layer, MoSi2/Si middle-layer and Si3N4/SiC/Si thin surface-layer. The MoSi2/Si middle-layer, whose thickness could be controlled by dipping process, is the main portion of coating. Oxidation test reveals that the Mo-Si-C-N multi-layer coating significantly improves the oxidation resistance of the C/C composites. Compared with the Mo-Si-C coating, the oxidation temperature is extended up to 1450°C. After oxidation pre-treating at 1400°C, the anti-oxidizing temperature of the Mo-Si-C-N multi-layer coated C/C composites can be raised to 1500°C and the weight loss is less than 1wt% after 12-hour oxidizing test.