Particle reinforced Sn-Zn based composite solders were obtained by adding Cu powders to Sn-9Zn melts. The microstructure analysis reveals that in situ Cu_5Zn_8 particles are formed and distributed uniformly in the composite solders. The strength and plasticity of the composite solders were improved, and creep resistance was considerably enhanced. The wettability of these composite solders is also better than that of Sn-9Zn.