Abstract: The influences of Bi on the melting point and wettability of Sn-0.3Ag-0.7Cu lead-free solder alloy were studied.The contrastive experiments and analysis on the melting point, wettability of Sn-0.3Ag-0.7Cu-xBi (x=0, 1, 3, 4.5)solders were carried out by differential scanning calorimetry and wetting balance equipment. Results show that the addition of Bi can decrease the melting point and improve the wettability of Sn-0.3Ag-0.7Cu lead-free solder alloy.But the amount of Bi should be limited.Because the excess element of Bi could increase the melting range of solder, decrease the plasticity of solder and result in the flaw of fillet lifting.Sn-0.3Ag-0.7Cu-3.0Bi lead-free solder performed an excellent cornprehensive properties.