The　impact　of　the　addition　of　salinity　on　partial　nitrification　and　anammox　(PN/A)　was　investigated　in　this　study.　The　sludge　was　immobilized　by　polyethylene　glycol　(PEG)-modified　polyvinyl　alcohol　(PVA)-sodium　alginate　(SA)　immobilization　technology,　and　the　effective　diffusion　coefficient　(D-e)　of　the　immobilized　particles　was　measured　to　be　0.313　x　10(-9)　m(2).s(-1),　indicating　that　the　system　has　excellent　mass　transfer　performance.　An　experiment　was　carried　out　by　adding　NaCl　to　create　a　salinity　gradient.　It　was　found　that　the　initiation　of　partial　nitrification　was　achieved　at　a　concentration　of　10　g.L-1　NaCl　and　the　nitrite　accumulation　rate　(NAR)　reached　81.03%,　which　could　provide　sufficient　NO2--N　for　subsequent　anammox.　Additionally,　an　anammox　reactor　operating　at　the　same　salinity　maintained　a　stable　state　after　acclimation,　and　the　removal　rates　of　NH4+-N　and　NO2--N　reached　80%.　The　dominant　population　in　the　anammox　system　was　Planctomycetes.　Salinity　is　a　feasible　factor　for　controlling　the　PN/A　process.