Abstract: Lead-containing solders have been used in attaching components and printed circuit boards (PCBs) in electronics industry due to their unique characteristics of excellent economical efficiency,practicability and reliability that are well suited for electronics applications. However,over lead ending up in landfill would contaminate land and water supplies,and over lead would resist recycling operations,it is inevitable that lead-containing solders must be replaced by lead free solder. The electronics industry begins to focus upon the tin-silver-copper system alloys as they have the advantages of good reliability and good solderability. A review of the research development of microstructures and properties of tin-silver-copper system alloys in recent years is made. It shows no advantages in terms of processing,reliability,or availability for the high-silver alloys as compared to the low-silver alloys. The result could provide the basis for selecting the optimal solder alloy in this system.