Due　to　the　asymmetric　structure　of　Sn　unit　cell,　the　electromigration　behaviors　of　Sn　based　solder　joints　were　significantly　depended　on　the　crystal　orientation　of　Sn　grain.　The　present　investigation　illustrated　the　effect　of　Sn　grain　c-axis　on　the　intermetallic　compounds　(IMCs)　growth　under　current　stressing.　The　Cu　particles　reinforced　Sn3.5Ag　solder　joint　was　selected　to　obtain　various　observed　surfaces　of　the　sample　after　46　days　current　stressing.　The　front　side,　back　side,　right　side　and　anode　side　of　the　sample　represented　different　phenomena,　which　reflected　and　proved　the　importance　of　c-axis　orientation　on　Cu　atomic　migration　in　three-dimension　space.　Besides,　another　composite　solder　joint　was　polished　severe　times　on　the　observed　surface　which　was　full　of　IMCs.　It　showed　that　the　IMCs　were　covered　on　the　Sn-based　solder,　and　there　was　crack　at　the　cathode　underneath　the　front　surface　after　38　days　current　stressing.　The　IMC　growth　behavior　would　be　well　understood　by　systematic　study　in　this　work.