Plasma surface alloying process was employed to prepare molybdenizing coating on TC4 alloy. Microstructural characteristics of the molybdenizing coating were analyzed using optical microscope (OM), glow discharge optical emission spectrometer analysis (GDOES) and X-ray diffraction (XRD). Corrosion resistance of molybdenizing coating and TC4 alloy in simulated oilfield medium were estimatted via electrochemical measurements. The results revealed that the uniform and continuous molybdenizing coating was composed of a deposition layer and a diffusion layer. The molybdenizing coating presented slightly lower corrosion resistance as compared with TC4 alloy.