To　compare　the　effect　of　two　different　operational　modes　on　partial　nitrification　(PN),　two-stage　continuous　stirred-tank　reactors　(CSTR)　1#　(anoxic-oxic)　and　2#　(controlling　DO　and　HRT)　were　constructed　and　operated　at　room　temperature　(18-22　℃).　Start-up　time,　stability,　aeration　consumption,　sludge　settling　ability,　as　well　as　the　adaptability　to　the　decreasing　of　ammonia　nitrogen　concentration　were　investigated.　PN　in　1#　and　2#　were　accomplished　in　26　d　and　41　d,　respectively.　When　the　effluent　of　an　anaerobic/oxic　(A/O)　process　for　phosphorous　removing　(containing　ammonia　nitrogen　35-43　mg/L)　was　used　as　influent,　PN　was　stable　both　under　1#　and　2#　condition,　however,　aeration　consumption　could　be　reduced　by　about　20%　in　2#.　When　the　ammonia　nitrogen　decreasing　from　43　to　27　mg/L,　PN　in　1#　would　be　unstable　and　the　rates　of　PN　decreased　to　67.39%.　For　comparison,　PN　in　2#　could　be　maintained　stable　with　an　ammonia　removal　rate　of　＞88%.　Settleability　of　sludge　was　good　both　in　1#　and　2#.　Rapid　start-up　could　be　achieved　through　controlling　DO　and　HRT,　and　a　stable　and　efficient　PN　could　be　maintained　through　anoxic-oxic.　©　2016,　Editorial　Board　of　Journal　of　Harbin　Institute　of　Technology.　All　right　reserved.