Experiments　were　conducted　to　study　the　performance　characters　of　aerobic/anoxic　(A/A)　digestion　of　sludge　at　30±1°C,　while　the　sludge　retention　time　(SRT)　was　kept　16　d.　The　variations　of　oxidation　reduction　potential　(Eh)　and　pH　were　continuously　monitored　during　the　A/A　digestion　and　the　conversions　of　ammonium　and　nitrate　were　investigated.　Important　features　on　both　Eh　and　pH　profiles　were　identified　to　develop　process　control　strategy.　Since　the　feature　point　on　Eh　profile　where　d2　Eh/dt2=0　is　very　stable　during　anoxic　cycle,　it　can　be　used　to　determine　the　end　of　denitrification.　The　end　of　nitrification　can　be　identified　according　to　dpH/dt=0.　A　real-time　control　strategy　of　A/A　digestion　of　sludge　was　developed　and　tested　with　pH　and　Eh　as　control　parameters.　It　is　shown　that　the　performance　of　the　real-time　control　strategy　is　better　than　that　of　a　fixed-time　control　strategy.　While　the　real-time　controlled　A/A　digestion　system　can　achieve　a　similar　volatile　suspended　solids　(VSS)　destruction　efficiency　of　35.2%　as　a　continuously　aerated　system,　it　improves　the　supernatant　quality　in　a　shorter　aeration　time(7.75　d　for　a　20　d　period).　Copyright.