Removal　of　trace　phosphorus　in　water　is　investigated　by　iron-aluminum　composited　adsorbent.　Adsorption　mechanism　of　phosphorus　removal　is　approached　by　analysis　methods　such　as　particle　size　analysis,　zeta　potential　and　scanning　electron　microscopy.　Results　show　that　the　absorbent　is　provided　with　more　effective　phosphorus　removal　efficiency,　which　is　clearly　better　than　those　of　Fe2O3　and　active　aluminum　oxide　(7-Al2O3)　under　the　same　condition.　When　initial　ρ(PO43--P)　is　0.3　mg/L,　the　adsorption　capacity　is　as　high　as　about　1.5　times　of　Fe2O3　and　2.5　times　of　γ-Al2O3.　The　adsorbent　is　proved　with　property　of　hyperfine　powder.　The　specific　surface　area　reaches　184.45　m2/g,　which　is　9.15　times　as　large　as　that　of　Fe2O3.　One　of　the　main　reason　of　effective　adsorption　to　phosphorus　is　that　aluminum　embedment　and　lattice　disruption　and　micro-crystallization　caused　by　grinding　during　preparation　process.　The　zero　potential　is　6.2.　Another　main　reasons　of　effective　adsorption　to　phosphorus　is　no-specific　and　strong　specific　adsorption　existed　on　adsorbent　surface　in　water　treatment　process.