Giant reed (GR) was modified into giant reed quaternary amino anion exchanger (GR-QE) for the removal of phosphate by reacting with epichlorohydrin, ethylenediamine (EDA) and triethylamine in the presence of N,N-dimethylformamide (DMF). Factors like GR dosage, temperatures and volumes of organic liquid chemicals were used in single-factor experiments and orthogonal experiments for determining optimal conditions, with phosphate removal efficiency and zeta potentials as indicators. The results indicated that the optimal conditions obtained in the orthogonal experiments were consistent with those in the single-factor experiments. The GR utilization on a large-scale was realized, and the dosage of EDA was considered as the key influential factor in the preparation of GR-QE. Under these conditions, the nitrogen content in GR-QE was about 7.78%, while it was 0.9% in GR. The phosphate removal was about 82.1%, zeta potential was 23.2 mV. (C) 2009 Elsevier B. V. All rights reserved.