Sip/4032Al composites for electronic packaging applications with high volume fraction of Si particles were fabricated by squeeze-casting technology. The microstructure observation showed that the composites were dense and Si particles distributed uniformly, The interfaces and the existance of the interface reaction were the important factors which affected the properties of the composites; The linear CTEs of Sip/4032Al composites was between (8.1~12) ×10-6°C-1, and they were decreased with the increasing content of Si particles as well as annealing treatment. Kerner model can predict the CTEs of Sip/4032Al composites moderately; the thermal conductivity can reach 103W/ (m·°C), which was decreased with the increasing contents of Si particles as well as annealing treatment. The thermal conductivity of composite calculated was larger than tested values. The composites had excellent mechanical properties and also could be recycled.