Abstract: Eutectic alloy has good laser welding performance. To improve the strength and maintain good theromphysical properties of Al-12Si alloys for the electronic packaging cover material plate, the Al-12Si alloys were prepared by spray deposition and hot-pressing sintering technology. The effect of adding 0.6% Mg on the microstructure, mechanical properties, and thermophysical properties of the alloy were investigated. Results show that Si phase in spray deposited/hot pressed sintered Al-12Si alloy exhibits near spherical shape with an average size of (4.5±0.2)μm, which is homogeneously distributed in the Al matrix. The addition of Mg has not significant effect on the size and morphology of the Si phase, but Mg₂Si and β" secondary phases are formed in the Al matrix. Compared with Al-12Si alloy, the decrease of thermal conductivity of Al-12Si-0.6Mg alloy is only 4.2%, but the tensile strength has increased from 154.1 MPa to 190.1 MPa, with an increment of 23.4%, which is mainly attributed to solid solution strengthening and precipitation strengthening.