The　process　of　anaerobic　ammonium　oxidation　(Anammox)　requires　a　proper　ratio　of　NH4+-N　and　NO2--N　in　the　influent,　which　is　difficult　to　control　upon　treating　domestic　wastewater.　In　this　study,　a　control　strategy　of　semi-nitritation　(SN)　process　based　on　monitoring　the　pH　profile　and　NH4+-N　concentration　in　a　sequencing　batch　reactor　(SBR)　was　developed.　The　aeration　time　of　each　cycle　in　SN-SBR　was　calculated　using　the　established　equation　t(SN)　=　t(COD)　+　0.56　alpha　nS(0)/(S-0　-　S-n).　To　verify　the　suitability　of　the　control　strategy,　SN-SBR　was　operated　continuously　for　20　cycles,　fed　with　real　domestic　wastewater　with　a　fluctuating　COD　of　200-400　mg　L-1　and　NH4+-N　of　65-80　mg　L-1.　The　nitrogen　removal　performance　of　SN-anammox　system　using　the　developed　control　strategy　was　also　monitored.　Results　showed　that　SN-SBR　was　able　to　generate　a　suitable　ratio　of　NH4+-N　to　NO2--N　for　the　following　anammox　process,　the　TN　removal　rate　of　the　SN-anammox　system　achieved　91.7　+/-　0.4%　and　the　average　ammonium,　nitrite　and　nitrate　concentration　of　effluent　was　only　0.50　+/-　0.24,　0.13　+/-　0.09　and　4.9　+/-　0.22　mg　L-1,　respectively.　This　study　has　potential　application　in　the　treatment　of　domestic　wastewater　using　combined　SN-anammox　process.　(C)　2015　Elsevier　Ltd.　All　rights　reserved.