The　effects　of　Sn　and　Nb　additions　on　the　corrosion　resistance　of　Cu-2.89Ni-0.61Si-0.14Mg　alloy　in　3.5　wt%　NaCl　solution　were　investigated.　The　results　show　that　the　additions　of　Sn　and　Nb　can　improve　the　corrosion　resistance　of　Cu-Ni-Si-Mg　alloy.　The　sample　with　0.2　wt%　Nb　exhibits　better　corrosion　resistance　than　the　sample　with　0.2　wt%　Sn.　Compared　with　the　dopant-free　sample,　for　the　0.2Sn-doped　sample　and　0.2Nb-doped　sample,　the　values　of　corrosion　current　densities　decrease　by　7%　and　21%,　and　the　values　of　polarization　resistances　increase　by　5%　and　21%,　respectively.　The　corrosion　film　of　Cu-Ni-Si-Mg　alloy　is　a　double-layer　structure.　The　additions　of　Nb　and　Sn　are　helpful　to　improve　the　density　of　the　outer　layer　of　corrosion　film　and　increase　the　charge　transfer　resistance　of　the　inner　layer　of　corrosion　film.　The　additions　of　Sn　and　Nb　can　refine　and　uniform　the　microstructure　of　alloy,　which　is　helpful　to　the　formation　of　a　more　complete　corrosion　layer.　Cu2O　and　CuO　are　the　corrosion　products　of　alloys,　and　the　content　of　Cu2O　can　be　increased　by　the　Sn　and　Nb　additions.