One of the most important methods to investigate heavy metals as pollutants is more likely to use bio-monitors which can be applied as an appropriate index to express the quality of environment. In current study, in order to investigate the effects of dominant plants in the desired region and role of aquatic macrophytes in monitoring such elements as zinc (Zn), lead (Pb), copper (Cu) and cadmium (Cd) in underground organs, leaves and stems of a specific aquatic macrophyte named Phragmites australis as well as sediment samples of Dez River, Iran in 2012 were studied. Given samples were prepared with the ratio of 4 to 1 nitric acid to perchloric acid and the concentrations of elements were measured by atomic absorption spectrometry. In this study, Enrichment Factor (EF), Bio-accumulation Index and Translocation Factor (TF) were measured. Results indicated that the concentration of metals was reduced in the underground organs, leaves and stem, respectively (stem