In　this　work,　the　Cu-Ni-Si　alloy　sheets　with　a　thickness　of　1.5　mm　were　prepared　by　constrained　groove　pressing　(CGP)　and　aging　treatments.　The　results　show　that　the　combination　of　CGP　and　aging　treatments　can　simultaneously　improve　the　mechanical　properties　and　electrical　conductivity　of　alloy.　The　sample　subjected　to　10　passes　of　CGP　treatment　and　aged　at　460　°C　for　1　h　exhibits　optimal　comprehensive　properties,　with　a　hardness　of　234.8　HV,　an　ultimate　tensile　strength　of　773.5　MPa,　an　electrical　conductivity　of　38.1　%IACS,　and　a　favorable　breaking　elongation　of　15.7　%.　Compared　to　the　peak-aged　sample　without　CGP　treatment,　the　hardness,　ultimate　tensile　strength　and　electrical　conductivity　increase　by　12.4　%,　15.1　%　and　5.5　%,　respectively.　The　CGP　treatment　can　refine　the　grain　size　of　alloy　and　increase　the　dislocation　density,　thereby　promoting　the　precipitation　of　solute　atoms　during　the　aging　process.　The　aged　sample　subjected　to　CGP　treatment　has　a　higher　quantity　of　δ-Ni2Si　precipitates,　and　the　formation　of　Ni3Si2　precipitates　is　inhibited.　After　aging　treatment,　the　proportion　of　Σ3　grain　boundary　increases　in　the　sample　subjected　to　CGP　treatment.　Compared　to　random　grain　boundaries,　the　adjacent　grains　on　both　sides　of　Σ3　grain　boundaries　have　a　smaller　Schmid　factor　mismatch,　which　helps　to　improve　intergranular　deformation　compatibility.　Moreover,　the　scattering　effect　of　Σ3　grain　boundaries　on　electrons　is　smaller.　Therefore,　the　higher　proportion　of　Σ3　grain　boundary　can　improve　the　ductility　and　electrical　conductivity　of　Cu-Ni-Si　alloy.　©　2025　Elsevier　B.V.