Abstract: Carbide reinforced metal matrix surface composites have the advantages of high hardness,high modulus of carbide and the high toughness and high plasticity of the matrix,which is an effective way to improve the service life of metal materials.However,with the increase of carbide particle volume fraction,the strength of the composites increases significantly while the toughness decreases significantly.How to improve the strength and toughness inversion of ceramic/metal composites has become one of the basic problems in the field of composite research. At present,the reported toughening methods of carbide/metal-based surface composites mainly include surface gradient,nanocomposite,surface stress and new structure.The importance of metal surface engineering technology and the research progress and preparation status of surface gradient enhancement layers were discussed. The advantages of the surface gradient reinforcement layer were discussed in detail,and the surface treatment technology was proposed to prepare carbide ceramic gradient composite layer on the metal-based surface,in order to realize the continuous or step-by-step change of the surface reinforcement of the parts,while maintaining the good performance of the matrix,which was expected to improve the service performance of the metal material,enhance the surface characteristics,and prolong the service life.It has important engineering practical value.