Granulation　of　halophilic　activated　sludge　is　an　important　solution　to　solve　the　problem　of　solid-liquid　separation　in　biological　treatment　of　saline　wastewater.　This　study　demonstrated　that　by　adding　divalent　cations　into　the　saline　influent　with　low　organic　load,　halophilic　granular　sludge　with　an　average　diameter　of　910　±　10　μm　can　be　cultivated.　The　close　correlation　between　divalent　cations　and　particle　size　indicated　that　Ca2+　played　a　major　role　in　the　granulation　process.　Ca2+　was　accumulated　in　halophilic　granular　sludge,　which　provided　an　inorganic　carrier　for　microbial　aggregation　and　leaded　to　the　dominance　of　halophilic　bacteria　of　the　family　Flavobacteriaceae.　The　halophilic　bacteria　secreted　a　large　amount　of　extracellular　polymeric　substances　(EPS),　which　contained　70.0　±　0.02%　protein.　By　enhancing　the　EPS　network　of　protein　and　Ca2+,　halophilic　granular　sludge　was　formed.　The　addition　of　Mg2+　enhanced　the　network　of　Mg2+　and　loosely　bound　EPS,　which　could　be　destroyed　due　to　Na+　substitution.　This　study　provides　an　effective　granulation　method　for　halophilic　activated　sludge.　©　2020　Elsevier　Ltd