Abstract: The interface morphology between WC enhanced Ni base self-fluxing alloy coating and 3SCrMoAI steel substrate,which were fabricated respectively by oxyacetylene flame spraywelding,plasma spraying+oxyacetylene flame re-melting, plasma spraying + re-melting in electric furnace, was investigated. The results show that the composition diffusion between the coatings and substrate occurs during the coatings-melting process,which mainly is Fe element in substrate diffusing into the melted coating. The composition diffusion has definitive influence on the interface morphology. When the temperature of substrate surface is high enough, there will be amount of Fe element diffusing into the coating, and a thin and dense layer of Fe-Ni solution phase forms at the interface between the coating and substrate. So the adherent strength will be improved remarkably and the coating will have excellent anti-spell property.