To　achieve　the　approriate　trade-off　between　the　low　charing　delay　and　enough　self-protection　ability　in　the　NI　REBCO　coil,　the　controllable　Cu　layer　structure　in　REBCO　tape　is　essential,　which　can　cause　required　electrical　and　thermal　properties　in　both　the　radial　and　circumferential　direction.　In　this　paper,　the　cor-relation　between　the　material　characteristics　of　the　copper　layer　on　the　electrical　and　thermal　properties　of　REBCO　was　explored　by　investigating　the　REBCO　tape　with　different　Cu　layer　thicknesses.　The　influence　of　charging　decay,　self-protection,　and　cold　shrinkage　stress　on　the　REBCO　coil　performance　was　also　evaluated　based　on　three　tapes.　Three　new　findings　showed　the　possible　dominant　factor　on　electrical　and　thermal　properties　in　either　radial　or　circumferential　direction.　Unlike　the　traditional　electroplated　layer,　the　Cu　layer　in　the　SP3　sample　has　piecemeal　Cu　grains,　which　may　be　the　primary　factor　in　significantly　increasing　the　electrical　resistivity　and　decreasing　the　thermal　conductivity　significantly.　In　the　radial　direction,　the　nonuniform　top,　bottom,　and　even　side　thickness　of　the　Cu　layer　could　increase　the　electrical　resistivity　and　thermal　conductivity.　And　the　bad　corner　contact　quality　between　the　Cu　and　Ag/REBCO　could　be　an　im-portant　factor.　Furthermore,　the　Cu　layer　purity　may　be　significantly　lower　than　previously　thought.　Using　the　electrical　resistivity　and　thermal　conductivity　values　of　pure　Cu　as　the　Cu　layer　in　the　simulation　could　result　in　significant　errors.　This　study　provides　possible　directions　for　finding　a　method　to　control　the　properties　of　the　Cu　layer　of　REBCO　commercial　tape,　which　can　better　fit　different　application　scenarios.(c)　2022　Elsevier　B.V.　All　rights　reserved.