Abstract: The cadmium-free silver filler metal Ag30CuZnSn-3Ga-2In has excellent comprehensive property.In this paper,the effects of rare earth,called usually "vitamin" of metals,Ce on microstructures of Ag30CuZnSn-3Ga-2In filler metal were studied.Results showed that the rare earth Ce did not dissolve into Ag based solid solution and Cu based solid solution,but could form rare earth phase which acted as the particle of "out-of-phase nucleation" in the filler metal matrix.Enrichment phenomena could be confirmed for rare earth Ce in the grain boundary.It is found that rare earth Ce can fine grain strengthen grain boundary and exhibit the formation of Cu₆Sn₅ for the silver filler metals bearing Ga and In.It is found that adding 0.1% rare earth Ce can improve the microstructure of the Ag30CuZnSn-3.0Ga-2.0 filler metals grealy.