Micro-arc oxidation is a surface-treatment technology to in-situ form ceramic coatings on surfaces of valve metals including Al, Mg and Ti and corresponding alloy. The coatings obtained by micro-arc oxidation are closely adhesive to metal substrates and can improve wear resistance, corrosion resistance, thermal shock resistance and insulativity of materials. With development and formation mechanism of micro-arc oxidation as anentry point, similarities and differences between single al- loy and metal composite were compared. It was found that the formation mechanism was mainly based on electric breakdown theory. The micro-arc oxidation will be accelerated if second phase of the metal composite was valve metal. The micro-arc oxidation will be hindered if the second phase was formed by other metal elements (other than valve metals), which made the mechanism complicated. Effects of electrolyte, additives, voltage, current density, frequency, duty cycle, temperature and treatment time on micro-arc oxidation process of metallic composite, coating microstructure, phase composition, thickness, hardness, wear resistance and corrosion resistance were summarized. Finally, current problems in micro-arc oxidation of the metal composite were put forward. It was proposed to strengthen the mechanism research, optimize the process parameters, improve micro-arc oxidation devices and combine with other technologies in order to improve accelerate micro-arc oxidation, improve performance of ceramic membrane and promote application of micro-arc oxidation technology.