The tensile strength, early strength, long time intensity changes of Sn-Zn lead free solder are better than the Sn - Pb solder; In terms of the ductility, Sn-Zn solder has the same perofomance as Sn-Pb solder. In addition, Zn has low toxicity and low cost. If the mechanical strength, melting point, cost and toxicity of solder alloy are considered, it is more suitable to replace Sn-Pb solder with Sn-zn solder.