The　aim　of　this　study　is　to　deeply　study　and　analysis　of　energetic　performance　of　the　novel　coupled　system　composed　of　a　two-stage　sodium　thermal　electrochemical　converter　and　a　two-stage　thermoelectric　generator.　The　main　methods　are　to　establish　the　model　of　the　coupling　system　by　considering　the　main　irreversibilities,　and　obtain　the　analytical　expressions　of　the　power　outputs　and　efficiencies　of　two　subsystems　and　coupling　system.　The　main　novelties　are　to　obtain　the　optimum　ranges　of　critical　parameters　of　the　coupled　system　and　give　the　reasonably　matching　conditions　between　the　subsystems.　The　main　contents　of　this　study　include　that　the　influences　of　the　intermediate　and　condenser　temperatures　of　the　sodium　thermal　electrochemical　converter　and　current　density　of　the　first　stage　sodium　thermal　electrochemical　converter　as　well　as　the　electric　current　of　the　two-stage　thermoelectric　generator　on　the　efficiency　and　power　output　density　are　discussed　and　the　maximum　power　output　density　and　efficiency　of　the　system　are　calculated　and　compared　with　those　of　the　single　two-stage　sodium　thermal　electrochemical　converter　and　the　existing　coupling　models.　Results　show　that　the　maximum　efficiency　and　maximum　power　output　density　of　the　coupled　system　attain　0.413　and　68.7　x　10(3)　W　m(-2)　and　exhibit　an　improvement　of　about　14.1%　and　66.7%　than　those　of　the　standalone　two-stage　sodium　thermal　electrochemical　converter　respectively,　and　the　maximum　efficiency　of　the　whole　system　increase　37.7%　compared　with　that　of　the　existing　coupling　system.　The　results　obtained　indicate　that　the　performance　of　the　proposed　system　is　greatly　improved　by　efficient　the　exhaust　heat　utilization.　In　addition,　the　multi-objective　and　multi-parametric　optimization　analyses　are　adopted　to　search　for　the　global　optimization　profile　and　validate　the　obtained　findings.