Abstract: 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.Resultsshow that the absorbent is provided with more effec- tive phosphorus removal efficiency,which is clearly better than those of Fe₂O₃ and active aluminum oxide (γ- Al₂O₃) under the same condition.When initial ρ(PO₄^3--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.