A　large　wastewater　treatment　plant　(WWTP)　could　not　meet　the　new　demand　of　urban　environment　and　the　need　of　reclaimed　water　in　China,　using　a　US　treatment　technology.　Thus　a　multi　AO　reaction　process　(Anaerobic/oxic/anoxic/oxic/anoxic/oxic)　WWTP　with　underground　structure　was　proposed　to　carry　out　the　upgrade　project.　Four　main　new　technologies　were　applied:　(1)　multi　AO　reaction　with　step　feed　technology;　(2)　deodorization;　(3)　new　energy-saving　technology　such　as　water　resource　heat　pump　and　optical　fiber　lighting　system;　(4)　dependable　old　WWTP＇s　water　quality　support　measurement　during　new　WWTP＇s　construction.　After　construction,　upgrading　WWTP　had　saved　two　thirds　land　occupation,　increased　80%　treatment　capacity　and　improved　effluent　standard　by　more　than　two　times.　Moreover,　it　had　become　a　benchmark　of　an　ecological　negative　capital　changing　to　a　positive　capital.