Abstract: In order to improve the soldering reliability of electronic products, the wettability and tensile properties of Sn43Bi57 brazing alloy and Cu welded joints under no magnetic field, steady constant magnetic field and cutting magnetic field were studied. The results indicate that the application of magnetic field significantly improves the wettability and reaction layer thickness between Sn43Bi57 and Cu. In the early stages of soldering, the cutting magnetic field effectively enhances the wettability of Sn43Bi57 solder on Cu plate, markedly increases the thickness of the intermetallic compound(IMC) layer, and simultaneously improves the tensile properties of Sn43Bi57 and Cu solder joints. Under prolonged holding at a constant temperature, the solder joints exhibit optimal wettability and tensile properties under constant magnetic field. Investigating the influence of magnetic fields on the microstructure and properties of Sn-Bi and Cu solder joints provides a basis for improving the soldering performance of Sn-Bi alloys.