To　estimate　the　dissolved　oxygen　(DO)　concentration　in　the　wastewater　treatment　process　more　accurately,　a　group　genetic　case-based　reasoning　(GGCBR)　soft-sensing　method　of　DO　concentration　is　proposed　by　the　integrated　use　of　genetic　algorithms　(GA)　and　group　decision　making　(GDM)　in　this　paper.　First,　an　attribute　weight　iterative　optimization　using　GA　is　discussed　in　the　case　retrieval　phase.　Then,　a　case　reuse　method　is　carried　out　by　using　the　GDM　theory.　Finally,　the　historical　data　of　DO　concentration　in　a　wastewater　treatment　process　are　used　to　carry　out　a　comparison　experiment　by　10-fold　cross　validation.　The　results　show　that　this　proposed　GGCBR　is　superior　to　other　methods　and　significantly　reduces　the　fitting　error　of　DO　concentration.　(C)　2015　Elsevier　B.V.　All　rights　reserved.