Abstract: The surface modification layer of electron beam cladding has phase transformation to form an enhanced phase, which can improve the properties of the metal material surface. The mechanism of phase change and the control of phase change structure of electron beam cladding surface modified layer were described. The mechanism of improving the mechanical properties, corrosion resistance and oxidation resistance of the modified layer by the microstructure was summarized. The influence of metallographic structure on the cracks and pores of the modified layer was briefly described, and the current problems of electron beam cladding technology were prospected.