In order to improve the high temperature oxidation resistance of niobium alloy, a molybdenum layer was firstly prepared on the surface of niobium alloy by electrodeposition method with uniform rotating cathode, and then the silicide composite coatings were obtained by the halide activated pack siliconizing. The formation and microstructure of as-deposited molybdenum layer and silicide coating were studied, and the high temperature oxidation behavior of C103 alloy with or without coating was compared and analyzed. The results showed that the current efficiency during electrodeposition was twice as high as that by conventional electrodeposition. The prepared molybdenum layer was amorphous with a cellular structure. After pack siliconizing, mainly MoSi2 and NbSi2 predominated the surface layer and intermediate layer of the composite coatings, respectively, and the composite coatings exhibited a strong interfacial bonding to the substrate. Thermally exposed to 1200 °C, the coated samples showed parabolic rate constants of 1.83×10-2 mg2cm-4h-1 and 8.08 mg2cm-4h-1, respectively. By comparison, a higher parabolic rate constant about 5.87×103 mg2cm-4h-1 was detected in the bare alloy, and pesting oxidation was found in the bare alloy only 10 h exposure. The composite coatings present excellent resistance to high temperature oxidation due to the formation of SiO2 surface scales during thermal exposure.