In　order　to　achieve　fuzzy　control　of　nitrification　in　a　Sequencing　Batch　Reactor　(SBR)　brewery　wastewater　was　used　as　the　substrate.　The　effect　of　alkalinity　on　pH　variation　during　nitrification　was　systematically　studied,　at　the　same　time　the　variations　of　DO　and　ORP　were　investigated.　Alkalinity　and　pH　of　the　wastewater　were　adjusted　by　adding　sodium　bicarbonate　at　five　levels　and　sodium　hydroxide　at　two　levels.　Unadjusted　wastewater　was　also　studied.　According　to　the　results,　variation　of　pH　could　be　divided　into　rising　type　and　descending　type.　When　bicarbonate　alkalinity　was　deficient　or　sufficient,　the　descending　type　happened.　If　alkalinity　was　deficient,　the　pH　decreasing　rate　got　slower　when　nitrification　nearly　stopped;　if　alkalinity　was　sufficient,　at　the　end　of　nitrification　pH　turned　from　decrease　to　increase.　This　was　the　most　common　situation　and　pH　could　be　used　to　control　the　end　of　nitrification.　When　alkalinity　was　excessive,　the　rising　type　happened,　pH　was　increasing　at　nearly　a　constant　rate　during　and　after　nitrification　and　could　not　be　used　to　control　the　nitrification　time,　but　if　the　aeration　rate　was　moderate　DO　could　be　used　to　control　the　nitrification　time.　This　situation　seldom　happened.　Therefore　the　variation　of　pH　could　not　only　be　used　to　control　the　nitrification　time　but　also　to　judge　whether　the　alkalinity　was　enough　or　not.　On　the　basis　of　this,　the　fuzzy　controller　of　nitrification　in　SBR　was　constructed.　When　discussing　the　influence　of　pH　on　nitrification　rate　the　composition　and　concentration　of　alkalinity　must　be　considered　or　else　the　results　may　be　incomprehensive.　And　to　some　extent　the　influence　of　alkalinity　on　nitrification　rate　was　more　important　than　pH.