The　high　adsorption　capacity　of　Fe3O4　and　C3N4　for　heavy　metals　and　the　amalgam　effect　of　Bi2O3　were　exploited　using　a　Fe3O4/Bi2O3/C3N4-modified　glassy　carbon　electrode　(GCE)　for　the　determination　of　Cd2+　and　Pb2+.　The　electrochemical　response　performance　of　the　Fe3O4/Bi2O3/C3N4/GCE　was　studied　by　square-wave　anodic　stripping　voltammetry.　The　electrochemical　conditions　were　optimized,　including　the　pH　of　the　buffer　solution,　content　of　Fe3O4/Bi2O3/C3N4　on　the　electrode　surface,　deposition　potential　and　deposition　time.　Under　optimum　conditions,　the　Fe3O4/Bi2O3/C3N4/GCE　sensor　shows　a　linear　response　from　0.01　μmol/L　to　3　μmol/L.　The　minimum　detectable　quantity　for　Cd2+　and　Pb2+　are　3　×　10−9　mol/L　and　1　×　10−9　mol/L,　respectively.　Interference　studies　were　carried　out.　The　sensitivity　of　the　Fe3O4/Bi2O3/C3N4/GCE　sensor　to　Cd2+and　Pb2+　does　not　significantly　change　in　the　presence　of　coexisting　heavy　metal　ions.　The　Fe3O4/Bi2O3/C3N4/GCE　sensor　exhibits　good　stability　and　repeatability.　The　Fe3O4/Bi2O3/C3N4/GCE　sensor　was　used　to　detect　Cd2+and　Pb2+　in　river　water　samples　to　demonstrate　its　real-world　application.　©　2020　The　Authors