Abstract: The superplasticity of aluminum matrix fabricated by spray atomization and co-dleposition was investigated. Before superplastic deformation, the pretreatment of hot compress and hot forward extrusion was utilized. Fine gains and uniformly distributed SiC_P in SiC_P/LY12 composite are observed. The results of superplastically uniaxial tension show that the SiC_P/LY12 composite has good superplasticity and the limit elongation and m-value are greatly affected by the temperature and strain rate. Moreover, the limit elongation is 345% in this compositewith 500℃ of temperature and 1.0×10^-3s^-1 of initial strain rate.