Characterizations　of　equivalent　thermal　conductivity　(ETC)　of　sintered　silver　is　an　important　topic　due　to　the　thermal-mechanical　reliability　requirements　of　electronic　packaging.　In　this　paper,　the　effect　of　various　types　of　cracks　on　the　ETC　of　sintered　silver　are　discussed.　A　numerical　method　to　simulate　the　heat　transfer　behaviors　of　porous　sintered　silver　containing　the　crack　effect　is　presented.　The　results　show　that　the　ETC　of　sintered　silver　depends　significantly　on　the　crack　length,　crack　orientation,　porosity,　and　pore　shape.　Theoretical　formulae　to　estimate　the　ETC　of　sintered　silver　are　also　presented,　in　which　the　effects　of　arbitrary　crack　depth,　arbitrary　crack　orientation,　arbitrary　porosity,　and　arbitrary　pore　shape　factor　on　ETC　are　included.　It　has　been　found　that　the　influence　of　the　side　edge　crack　on　the　reduction　of　the　ETC　of　sintered　silver　is　the　most　obvious　compared　with　the　center　crack　and　the　upper　edge　crack.　This　study　presents　a　quantitative　method　to　evaluate　the　crack　effect　on　the　ETC　of　porous　sintered　silver.