Abstract: A simple plasma spraying method was used to coat hydroxyapaptite (HA) on carbon/carbon composites(C/C composites) to endow their surface with bioactivity.The morphology,composition and interface of the HA coatings with different depths to the surface were systemically studied by using scanning electron microscopy,electron probe microanalyser and X-ray diffraction.Results indicate that the shorter the distance to the C/C substrates is,the higher the content of α-TCP and the decomposition degree of HA are.The morphology of the HA coatings with different depths to the surface are changed little.There is no obvious composition segregation of C,O,P and Ca in the interface of HA coating-C/C substrates.