To　solve　the　problem　of　breaking　and　floating　of　anaerobic　ammonium　oxidation　(anammox)　granular　during　reaction　may　lead　to　instability　or　collapse　of　the　treatment　system,　the　mechanism　and　control　strategy　of　anammox　granular　sludge　floating　were　summarized　in　this　paper.　The　previous　studies　showed　that　the　density　of　the　anammox　granule　decreased　which　was　thought　to　be　the　main　mechanism　of　granular　sludge　floating.　Therefore,　at　high　nitrogen　loading　rates　(NLRs)　level,　floating　would　occur　which　might　be　the　fact　that　the　anammox　granular　sludge　produced　a　large　amount　of　nitrogen　gas　(N2)　and　the　gas　could　not　release　easily.　Then　the　gas　trapped　in　the　granular　sludge　inside　or　attached　to　the　granular　sludge　surface.　There　were　some　strategies　which　were　adopted　to　control　the　anammox　sludge　floating,　such　as　controlling　the　particle　size　of　the　sludge　(1.5~4.0　mm);　controlling　the　NLRs　(4.0~34.5　kg/(m3·d));　improving　the　concentrations　of　phosphorus　and　calcium　in　the　influent　(ρ(KH2PO4)=10　mg/L,　ρ(CaCl2·2H2O)=0.15~5.65　mg/L);　using　the　reactor　with　stirring;　adjusting　the　location　of　outlet　and　controlling　the　time　of　output,　etc.　©,　2015,　Beijing　University　of　Technology.　All　right　reserved.