Abstract: Pot experiments were conducted to study the role of EDTA (1 mmol/kg and 3 mmol/kg), citric acid (5 mmol/kg and15 mmol/kg) and DTPA(1 mmol/kg and 3 mmol/kg) in phytoremediation of heavy metal-organic contaminated dredged sewage river sediment by Lolium multiflorum Lam. The results showed that the shoot accumulation amount of Lolium multiflorum Lam to heavy metal increased with adding 5 mmol/kg citric acid, but the result was not statistically different from the control. Increasing the adding amount of citric acid posed a severe phytotoxicity to Lolium multiflorum Lam by stunted growth and diminished uptake rates. With adding 3 mmol/kg EDTA and DTPA, the accumulation of Pb,Zn,Cu,Ni,Cd in shoots increased, while the concentration of chlorophyll decreased. pH of the sediment was decreased with adding 5 mmol/kg citric acid, while pH had little change with adding the other two chelators. With adding the three chelators, the bulk percentage of big particle sediment and the average particle size of sediment increased, while specific surface area and crystal lattice intensity decreased, which were contributed to the desorption of heavy metals from sediment particle; the amount of microorganism in sediment and the TOC content were increased; the catalase activity hasn’t much change. Compared with the control, the urease activity increased with adding 5 mmol/kg citric acid, but the result hadn’t attained remarkable level; the activity decreased with adding the other two chelators.