Ti2AlNb orthorhombic alloy is an attractive high temperature structural material for aero-industries, but insufficient wear-resistance is a major drawback which restricts the actual uses of this alloy in many circumstances. A double glow plasma surface molybdenizing on Ti2AlNb alloy had been carried out to resolve this problem. This paper investigated the electrochemical corrosion behaviors of the alloy after molybdenizing. The polarization curves of specimens in three corrosive media, 5% H2SO4, 5% HCl and 3.5% NaCl, were measured. The eroded surface morphologies were surveyed by SEM. The results indicate that surface molybdenizing decreased the alloy’s corrosion resistance slightly, but still exhibit good performance.