Using SHS reactive flame spraying, Al2O3- Al2Cu3 multiphase coating was produced on iron substrate surface taking Al and CuO as main reactants. Phase constituent and structure were analyzed and reactive procedure was discussed. The procedure of chemical combustion and structure transformation, reactive mechanism, and solidifying behavior during spaying were emphasized. It was revealed as follows. Formation of coating included double procedures respectively physical and chemical process synchronously and mutually affected with each other. In the latter process, it covered three successive stages of pre-heating, SHS combustion, structure formation and solidification. The process of pre-heating was controlled by melting and capillary movement of Al and reactive process between Al and CuO was controlled by indirect inter-diffusion through in-between laminar mainly composed of atom-ion melt. Due to remarkable temperature gradient and super-cooling degree, two kinds of morphology on Al2O3 were formed respectively of inner-crystalline solution in matrix with minimum diameter less than 100nm and large size of aggregated particles about microns. It similarly showed unevenness and imbalance during solidifying of Al and Cu mixture fusion.