The effects of interfacial thickness and temperature on thermal conductivity and CTEs of Al/SiC packaging materials were investigated. The interfacial thermal conductivity and thickness have significant influence on the thermal conductivity of the Al/SiC packaging materials, while the SiC size has slight influence on that of the Al/SiC packaging materials. The experiment results of thermal conductivity are similar to Hassleman model and simulation results. Schapery model can be used to calculate the CTEs of composites when temperatures are lower(50~100°C) and Kerner model can be used when temperatures are higher(300~450°C). The CTEs of composites will increase more quickly than that by three models when temperatures are between 100°C and 300°C.