Abstract: AlSi electro-packing composites are characterized by low coefficient of thermal expansion (CTE), high thermal conductivity, low density, etc. and thus can be used as the packing material of microwave T/R module. However, wettability of InSn solder is poor in low temperature welding, which affects normal production. Therefore, the relationship between wettability of InSn solder and T/R module surface state (nickel-gold plating) is discussed in this paper. The experiment and statistic show that roughness of the T/R module surface and thickness of nickel have great influence on wettability of InSn solder. 