The high silicon content Si-Al alloy is a typical heat dissipation material that used in the electrical packaging field. A spray forming process wais used to produce a 90%Si-Al alloy specimen as a heat dissipation material in the present study. Then the spray formed 90%Si-Al specimens weare hot pressed at 1000°C with different pressure ranged from 2MPa to 10MPa to increase their density. The physical properties of the experimental alloy specimen weare measured. And the microstructure wass are observed by using optical microscopy and scanning electronic microscopy. The results showed that the Spray forming wais suitable forto producinge a 90%Si-Al alloy. With hot pressure of 10MPa, the relative density value of 90%Si-Al reachedcan obtain 94%. The typical physical properties such as the thermal conductivity, coefficient of thermal expansion and electrical conductivity of 90%Si-Al alloy are acceptable as a heat dissipation material for many electronic packaging applications.