Effects of Pr addition on wettability, microstructure of Sn3.8Ag0.7Cu solder were studied, the mechanical properties of solder joints were investigated and the fracture morphologies were also analyzed in this paper. The results indicate that adding appropriate amount of Pr can evidently improve the wettability of solder, and it is also found that Pr can refine the β-Sn dendrites and reduce the intermetallic compounds growth inside the solder due to the fine PrSn₃ particles formed in the solder which can act as heterogeneous nucleation sites. Moreover, the joints soldered with the SnAgCuPr solders possess sound mechanical properties which may result from the finer microstructure improved by the Pr.