Given　the　great　concern　about　phosphorus　(P)　resource　depletion,　it＇s　promising　to　recover　P　from　waste　activated　sludge　(WAS)　especially　for　agricultural　application.　To　this　end,　it＇s　necessary　to　understand　the　P　speciation　and　fractionation　within　the　sludge　before　and　after　stabilization　and　precipitation.　In　this　study,　we　systematically　studied　P　species　and　distribution　within　WAS　after　anaerobic　digestion　and　chemical　precipitation　using　liquid　state　P-31　nuclear　magnetic　resonance　(NMR)　spectroscopy,　sequential　extraction　method　as　well　as　XRD　Technology.　P　transformation　and　bioavailability　were　also　discussed　with　the　obtained　results.　Inorganic　P　was　found　to　be　dominant　in　WAS　before　(67.6%)　and　after　digestion　(77.2%).　Vivianite　seems　to　dominate　among　the　P-containing　minerals　both　in　the　raw　and　digested　sludge　from　XRD　spectra.　In　the　NMR　spectra,　the　orthophosphate　(Ortho-P)　and　polyphosphate　(Poly-P)　were　two　dominant　species　in　the　raw　sludge.　However,　the　Poly-P　peak　vanished　after　anaerobic　digestion,　indicating　Poly-P　was　released　and　degraded　under　anaerobic　environment.　Fe3+　addition　and　Mg2+　addition　with　pH　adjustment　displayed　comparable　P　removal　efficiencies.　No　significant　differences　on　P　distribution　by　sequential　extraction　test　was　observed　after　P　precipitation.　Considering　that　no　pH　adjustment　was　needed,　it　might　be　more　cost　efficient　to　recover　P　by　iron　addition.