The　microstructure　and　the　mechanical　properties　of　a-phase　Cu-5Sn　alloy,　Cu-10Sn　alloy,　and　Cu-15Sn　alloy　(wt.%)　prepared　by　selective　laser　melting　have　been　studied　in　this　work.　Under　the　same　process　condition,　the　laser　absorption　of　the　alloys　increases　continuously　with　the　increase　in　Sn　content.　The　optimal　process　parameters　of　the　three　alloys　were　obtained　by　Response　Surface　Method.　The　Sn　content　was　found　to　have　a　significant　effect　on　the　relative　density　of　the　Cu-Sn　alloys,　as　well　as　the　laser　power.　The　effect　of　laser　power　on　the　relative　density　of　the　alloys　is　weakened　by　the　increase　in　laser　absorption　as　the　Sn　content　increases.　Comparing　the　melt　pool　of　the　three　alloys,　they　all　show　mainly　columnar　grains.　As　the　Sn　content　increases,　the　size　of　the　columnar　grains　becomes　larger,　and　when　the　Sn　content　reaches　15　wt%,　the　columnar　grains　can　penetrate　through　several　melt　pools.　With　the　increase　of　Sn　content　from　5　wt　%　to　15　wt%,　the　tensile　strength　of　the　alloy　increased　from　382　MPa　to　738　MPa,　but　the　plasticity　decreased　significantly　and　the　elongation　decreased　from　26%　to　9%.　As　the　Sn　content　increases　from　5　to　15　wt%,　the　amount　of　solid-soluble　Sn　in　the　a-phase　alloy　increases,　creating　a　lattice　distortion　stress　field　that　effectively　prevents　dislocation　movement.　Thus,　the　stress　field　effectively　increasing　the　yield　and　tensile　strength　of　the　alloy.　Meanwhile,　the　increase　in　Sn　content　leads　to　the　appearance　of　many　brittle,　hard　and　rich　phases　on　the　micron　scale　and　precipitation　from　grain　boundaries　within　the　lattice,　resulting　in　an　increase　in　strength　and　a　decrease　in　plasticity　of　the　alloy.　In　conclusion,　Cu-10Sn　alloy　has　more　excellent　tensile　properties　and　higher　yield　and　tensile　strengths　with　good　ductility　compared　to　Cu-5Sn　and　Cu-15Sn　alloys.　&　COPY;　2023　The　Authors.　Published　by　Elsevier　B.V.　This　is　an　open　access　article　under　the　CC　BY-NC-ND　license　(http://creativecommons.org/licenses/by-nc-nd/4.0/).