Polycrystalline　In4Se3　thermoelectric　materials　were　synthesized　in　the　processing　sequence　of　vacuum　melting,　annealing　and　spark　plasma　sintering.　The　effect(s)　of　melting　and　annealing　duration　periods　on　the　phase,　composition,　microstructure,　and　thermoelectric　properties　of　polycrystalline　In4Se3　were　investigated.　After　the　melting　process,　both　In　and　InSe　phase　were　detected　in　the　ingots.　With　increasing　melting　duration　time,　an　increase　in　Se　deficiency　was　observed,　leading　to　an　increase　of　carrier　concentration,　which　contributed　to　the　observed　improvement　of　electrical　conductivity.　The　specimen　melted　for　48　h　showed　relatively　higher　ZT.　Thus　on　the　basis　of　48　h　melting　process,　the　ingots　were　then　annealed　for　different　periods　of　time,　which　eliminated　the　presence　of　InSe　phase.　After　annealing,　scattered　large　step-like　structures　were　observed　in　the　matrix,　which　favored　the　reduction　of　thermal　conductivity　but　had　no　significant　influence　on　the　electrical　conductivity.　The　ZT　was　significantly　enhanced　to　0.83　at　702　K　by　extending　melting　and　annealing　duration　time　to　48　h　and　96　h,　respectively,　which　is　32%　higher　than　that　reported　in　literature.　It　was　concluded　that　both　the　extension　of　melting　and　annealing　duration　periods　could　improve　the　thermoelectric　performance　of　polycrystalline　In4Se3.