Combined with the research results of surface self-nanocrystallization at home and abroad, the generation mechanism of surface self-nanocrystallization layer, effects of self-nanocrystallization on surface hardness, friction and wear property, anti-fatigue property and corrosion resistance were overviewed and advantages and disadvantages of surface self-nanocrystallization were summarized. The latest progress of surface self-nanocrystallization and composite modification technology, which includes some conventional surface treatment methods such as the ion penetration and diffusion, micro-arc oxidation and electroless plating were introduced for the defects of surface nanocrystallization performance and single surface treatment technology. The great advantages of composite treatment technology in improving material properties were expounded. Finally, the challenges of duplex treatment were put forward. Starting from the research of strengthening mechanism, systematic research of composite treatment process and promotion of industrial application, the advantages of self-nanocrystallization of metal surface as the universal surface treatment method and other surface modification technologies are fully brought into play, thus providing reference and support for realizing the structural and functional integration of metal materials, promoting the research and development of high-performance new materials and high-performance composite surface layers, and accelerating the process of industrial application of composite modification technologies.