Abstarct: Regarding to the hazardous and permanent effects of heavy mextals in the environment and the necessity of removing them from different phases of the environment, in this study an effective method of cadmium removal from the contaminated soil has been proposed. For this purpose the using of nanoparticles as an effective method has been evaluated. In this study the process and mechanism of cadmium removal from contaminated soil by iron (III) oxide nanoparticles (Fe3O4) which are stabilized with Polyacrylic Acid (PAA) was evaluated. For this purpose, first, an appropriate composition with enough cadmium adsorption was selected after several preliminary tests and then was contaminated with cadmium nitrate. After preparation of contaminated soil, for providing of homogeneous nanofluid, the iron (III) oxide nanoparticles were stabilized with poly acrylic acid (PAA). Then the optimal environmental conditions for Cd removal were determined in the batch tests. Accordingly, the maximum removal rate (100%) of cadmium was obtained in the following conditions: nanofluid concentration=500 mg/L, pH=6.5, contact time=24 hr and the ratio of contaminated soil mass (gr) to nanofluid volume (mL) =1:150. Afterwards, with setting up a continuous flow configuration, optimal hydraulic conditions were determined. According the results of previous stage nanofluid with concentration of 500 mg/L and pH of 6.5 was used in this system and the removal rate of cadmium from the soil was up to 100% under the following conditions: nanofluid concentration=500 mg/L, pH=6.5, contact time=24 hr, and the flow rate =0.5 mL/min. After determination of optimal removal conditions in the both systems, selective sequential extraction on the contaminated soil before and after washing was performed. The distribution of cadmium in different fractions of the soil was carbonates, oxides and hydroxides, residual fraction, exchangeable, and organic matter respectively. The tendency of nanoparticles for removal of Cd2+ from the soil fractions was similar in the both system and it was in the order of : Exchangeable > carbonates > oxides and hydroxides > organic matter > residual Afterwards, additional experiments on nanofluid and soil, before and after Cd removal were implemented. Changing procedure of pH, EC, and TDS in soil and nanofluid, nanoparticle size and nanofluid zeta potential, XRD and SEM tests on the soil were tested for determination of physicochemicals changes in the soil and nanofluid after Cd removal process. Finally, the process of cadmium removal from the soil with iron (III) oxide nanoparticle was economically evaluated and verified.