Mode　fracture　behaviors　of　graphene　nanosheets　(GNSs)　reinforced　Sn-3.　0Ag-0.　5Cu(SAC305)　were　investigated　based　on　T-Peel　test　in　this　paper.　By　mechanical　mixture　of　GNSs　with　SAC305,　an　enhanced　mode　fracture　toughness　is　obtained　at　content　of　0.　10　wt%　GNSs.　Mode　fracture　toughness　of　SAC305　with　different　contents　of　GNSs　has　been　investigated.　Upon　adding　the　proper　GNSs,　the　cracking　path　in　SAC305　turns　to　be　cohesive　cracking　easily,　which　leads　to　increase　of　mode　fracture　toughness.　The　average　critical　energy　release　rate　obtained　at　content　of　0.　10　wt　%　GNSs　sac305　has　been　increased　by　94.　56%　and　the　maximum　critical　energy　release　rate　was　increased　to　2.　2　times　that　of　average　condition　in　SAC305　without　additive.　The　enhancement　mechanism　and　agglomeration　effect　of　GNSs　are　discussed　,　the　different　microstructural　characteristics　of　the　sample　after　mode　fracture　are　introduced.　The　fracture　properties　of　SAC305　with　different　graphene　additive　contents　are　discussed　and　clarified.　The　sintering　method　proposed　in　this　paper　meets　the　requirements　of　solder　joint　interconnection　technology.　This　study　presents　a　new　insight　for　adding　carbon-based　nanomaterials　to　electronic　packages　to　improve　the　mode　I　fracture　of　SAC305　solder.　©　2023　IEEE.