The slurry erosion-corrosion behaviour of TiN coated α-Ti alloy in aqueous silica slurry ontaining 3.5% NaCl has been investigated using a jet-in-slit rig. Erosion- orrosion tests were performed with slurry having jet velocity range 4.8-12.8 m s-1 and at normal impact angle. Because of synergistic effects between erosive wear and flow-induced corrosion, the erosion-corrosion rates of the TiN coating and a-Ti substrate were higher than the sum of erosive wear rates and flow-induced corrosion rates. At the lower slurry velocity, the TiN coating deposited on the a-Ti substrate presented better slurry erosion-corrosion resistance. With increasing slurry velocity, however, perforating, cracking and fragmenting of the hard TiN coating occurred and the protection effect of the coating layer reduced with the erosion-corrosion duration. And then the volume loss of the a-Ti substrate was enhanced through cracking of flakes induced by stress and corrosion.