Anaerobic　ammonium　oxidation　(ANAMMOX)　is　widely　used　for　treatment　of　ammonium-rich　wastewater　because　of　its　economic　and　environmental　benefits.　However,　ANAMMOX　bacteria　are　sensitive　to　environmental　conditions,　especially　to　heavy　metals.　The　short-term　and　long-term　effects　of　Ni()　on　ANAMMOX　were　studied　by　batch　and　continuous　flow　experiments,　respectively.　Results　showed　that　low　concentrations　of　Ni()　had　promoted　nitrogen　removal　by　ANAMMOX　and　high　concentrations　inhibited　ANAMMOX　performance　during　a　short-term　period.　Compared　with　the　specific　anaerobic　ammonium　oxidation　activity　(SAA)　without　Ni()　addition,　SAA　with　1　mg•L-1　Ni()　addition　increased　by　11.14%　and　the　SAA　with　100　mg•L-1　Ni()　addition　reduced　by　49.55%.　The　IC50　of　Ni()　for　ANAMMOX　was　determined　to　be　83.86　mg•L-1.　In　contrast,　long-term　Ni()　addition　significantly　suppressed　nitrogen　removal　of　ANAMMOX,　and　the　suppression　threshold　of　Ni()　on　ANAMMOX　was　15　mg•L-1.　The　Monod　model　was　applied　to　simulate　the　kinetics　of　ANAMMOX　without　Ni()　addition.　The　qmax0(TN/VSS)　and　KS0　values　were　12.25　mg•(g•h)-1　and　405.36　mg•L-1,　respectively.　The　modified　Haldane　model　was　suitable　to　describe　the　kinetics　of　ANAMMOX　with　50　mg•L-1　Ni()　addition.　The　qmax(TN/VSS),　KS,　and　Kivalues　were　6.78　mg•(g•h)-1,　313.2　mg•L-1,　and　1.32,　respectively.　The　inhibition　of　ANAMMOX　by　Ni()　is　anticompetitive　inhibition.　In　addition,　the　inhibition　of　Ni()　on　ANAMMOX　was　mainly　related　to　the　content　of　intracellular　Ni().　The　IC50intracellular　Ni()(VSS)　of　intracellular　Ni()　was　0.072　mg•g-1.　©　2020,　Science　Press.　All　right　reserved.