Sintered　silver　is　a　very　promising　die-attach　material　which　is　hopeful　to　be　adopted　in　the　third　generation　of　power　electronics.　Thermal　conductivity　is　an　important　index　to　characterize　the　heat　conduction　capacity　of　sintered　silver.　In　this　paper,　a　numerical　model　to　compute　equivalent　thermal　conductivity　of　sintered　silver　is　proposed　and　verified　based　on　the　method　with　microstructure　characteristics　modelling.　Based　on　the　computations,　the　variations　of　the　equivalent　thermal　conductivity　for　sintered　silver　are　presented　where　porosity　effect　and　aging　effect　are　taken　into　account.　Comparisons　of　heat　flux　distributions　and　temperature　distributions　of　sintered　silver　with　different　porosity　ratios　and　aging　time　are　also　made.　A　theoretical　model　is　proposed　to　evaluate　the　equivalent　thermal　conductivity　of　sintered　silver,　which　agrees　quite　reasonably　with　existed　experimental　results.　Based　on　the　proposed　model,　a　theoretical　model　to　predict　the　equivalent　thermal　conductivity　of　sintered　silver　considering　aging　effect　is　also　presented.　The　method　given　in　this　paper　can　be　used　to　predict　the　equivalent　thermal　conductivity　of　sintered　silver　under　different　loading　conditions　considering　aging　effect.