Abstract: The properties and microstructures of SnZnPr solders were studied with the addition of Au nanoparticles. The results indicat that the addition of Au nanoparticles can enhance the wettability of solder and the mechanical property of solder joints, the optimum content of Au nanoparticles is 0.1% with optimal design. However, excessive Au nanoparticles can degrade the wettability of solders, and no variation occurs for mechanical property of solder joints. With the microstructure observation of SnZnPr and SnZnPr-0.1Au solders, the 0.1% Au nanoparticles can refine the matrix microstructure of SnZnPr solder, especially for reduction of rich-Zn phases. Moreover, with the addition of 0.1% Au nanoparticles, nanoindentation testing indicates that the creep-resistance property can be enhanced obviously, thermal fatigue life of solder joints is increased by 12.3% with thermal cycling testing, which can be attributed to dislocation pinning effect of nanoparticles.