WC-12Co coating was prepared by high-velocity oxygen fuel (HVOF) spraying on Ti6Al4V alloy. The microstructure, phase structure and composition of the coating were investigated by SEM, XRD and EDS, respectively. Results show that the whole coating is dense, of low porosity and bonds well with the substrate. There is no lamination in the coating. The agglomerated particles bond closely with each other and they are dispersively distributed. It is attributed to the high speed of supersonic particles, which can make up for the pores caused by the irregular stacking fault to decrease the porosity and increase the density. The high speed particles deform sufficiently and it is beneficial to increase the area of the active region and good for the combining between the particles and the substrate, as well as particles and the coating. There are a few of Co3W3C and trace W2C besides WC in the coating; there is no metal Co, which has become amorphous. It is thought that W2C comes from the thermal decomposition of WC during spraying while the Co3W3C is the reaction product of Co and WC in the oxygen atmosphere and its small amount is due to the short time of the powder staying in the combustion chamber.