The　effects　of　Ag　content　on　the　melting　temperature,　wettability　and　mechanical　properties　of　the　soldered　joints　were　investigated.　Microstructures　and　shear　strength　of　SnAgCuX　soldered　joint　were　also　studied　under　both　as-reflowed　and　after　high　temperature　aging　conditions.　X　includes　Ni,　P　and　Ce　element.　The　experimental　results　indicate　that　the　addition　of　trace　amounts　X　element　can　remedy　the　decrease　in　properties　of　the　solders　to　a　certain　extent　due　to　the　decrease　of　Ag　content.　Adding　trace　amounts　of　X　element　has　little　influence　on　the　melting　temperature　of　the　solders,　but　obviously　improves　the　wettability　of　solder　and　the　shear　strength　of　the　soldered　joints,　and　markedly　decreases　the　effect　of　high-temperature　aging　on　shear　strength.　The　reason　may　be　related　to　the　modification　of　the　microstructure　and　IMC　of　the　solder　alloys　due　to　the　addition　of　trace　amounts　of　X　elements.