The investigation status of Sn-Ag lead-free solders Is reviewed comprehensively. The effects of Bi,In,Zn,Al,Cu,Ni,Sb et al rare earths and nanoparticles on the wetting properties,melting temperature,mechanical properties,microstructure and interfacial reactions are discussed. In addition,the problems in the study of Sn-Ag solders are discussed and solutions are proposed. It provides a reference for the research of Sn-Ag lead-free solder.